Group robot system, and sensing robot and base station used therefor

ABSTRACT

Communication system of a group robot system is made hierarchical, having a base station as an uppermost layer and a plurality of layers formed by a plurality of sensing robots, and the plurality of sensing robots are controlled such that a sensing robot belonging to an upper layer of the hierarchical structure has higher sensing resolution than a sensing robot belonging to a lower layer of the hierarchical structure. Thus, a group robot system capable of efficiently searching for an object can be obtained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a group robot system in which a numberof robots searching for an object operate collectively, as well as to asensing robot and a base station used therefor.

Conventionally, referring to FIG. 62, Japanese Patent Laying-Open No.8-30327 discloses a single or a plurality of sensor mechanisms forcollecting information of external environment, a practical environmentrecognition system operating in an actual environment and having ahierarchical information processing mechanism generating from sensorinformation {circle around (1)} from the sensor mechanism, appropriatemotion instruction {circle around (2)} for an actuator mechanism, and anintelligent robot. According to this technique, in accordance with thestate at the time of sensing, the hierarchical information processingmechanism provides motion instruction {circle around (2)} such that theactuator mechanism appropriately changes position of itself or of anobject as well as external environment such as illumination, so that thesensor mechanism functions satisfactorily.

2. Description of the Background Art

In the technique described in Japanese Patent Laying-Open No. 8-30327,the plurality of sensor mechanisms and sensor information processingunits from upper to lower orders are always in operation.

In a robot system using other sensing robot, all sensors performssensing with same sensitivity, that is, the same sensing resolution.

Therefore, when an object of searching is detected, a sensing robotsearching in a region far from the object of searching performs thesearch with the same sensing resolution as that of a sensing robotsearching in a region close to the object of searching.

As a result, it has been difficult to alleviate burden resulting fromprocessing the sensor information of the sensing robot and to reducepower consumption of the sensing robot. Further, as all the sensingrobots have uniform sensing resolution, it has been impossible to setsensing resolution of a specific sensing robot. Therefore, it has beendifficult to set higher the sensing resolution after detecting theobject of searching and to grasp detailed overall information of theobject of searching in a short time period.

Therefore, in the conventional group robot system, it has been difficultto efficiently search for the object.

An object of the present invention is to provide a group robot systemcapable of efficiently inspecting an object when an object of searchingis detected, as well as to provide a sensing robot and a base stationused therefor.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides a grouprobot system, including a plurality of sensing robots used for searchingfor an object, and a base station controlling the plurality of sensingrobots, wherein the plurality of sensing robots are controlled such thatmanner related to searching for the object differ dependent on thedistance from the base station.

Because of this configuration, the plurality of sensing robots arecontrolled such that the manner related to searching for the objectdiffer in accordance with the distance from the base station, andtherefore efficient searching of the object becomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, the manner related to searching for the object may bethe sensing resolution of each of the plurality of sensing robots.

Because of this configuration, the sensing resolution of each sensingrobot may be adjusted in accordance with the distance from the basestation, and efficient searching of the object becomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, the plurality of sensing robots may consist of aplurality of groups in accordance with the distance from the basestation, and sensing resolutions of the plurality of sensing robots maybe controlled such that the sensing robots of the group close to thebase station have higher resolution than the sensing robots of the groupfar from the base station.

According to the above described configuration, sensing resolution ofsensing robots are set higher in a group closer to the base station, andhence efficient searching of the object becomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, sensing resolution of the plurality of sensing robotsmay be controlled such that a sensing robot closer to the base stationhas higher resolution than a sensing robot far from the base station.

According to the above described configuration, sensing resolution of asensing robot closer to the base station is set higher, and henceefficient searching of the object becomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, the manner related to searching of the object may bethe speed of movement of each of the plurality of sensing robots.

In accordance with the above described configuration, the speed ofmovement of each sensing robot is adjusted in accordance with thedistance from the base station, and efficient searching of the object isperformed.

In the group robot system in accordance with the first aspect of thepresent invention, the plurality of sensing robots may consist of aplurality of groups in accordance with the distance from the basestation, and the speed of movement of the plurality of sensing robotsmay be controlled such that the speed of the sensing robots in a groupclose to the base station is slower than the speed of the sensing robotsof the group far from the base station.

By the above described configuration, the speed of movement of thesensing robots is set higher in a group closer to the base station, andefficient searching of the object becomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, the speed of movement of the plurality of sensingrobots may be controlled such that the speed of a sensing robot close tothe base station is slower than sensing robot far from the base station.

By the above described configuration, the speed of movement of thesensing robot closer to the base station is set slower than sensingrobot far from the base station, and efficient searching of the objectbecomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, the sensing robot is a fluttering sensing robot thatcan fly through fluttering motion, and the manner of searching for anobject may be the frequency of fluttering motion of the plurality offluttering sensing robots.

In accordance with the above described configuration, the flutteringfrequency of fluttering motion of each of the fluttering sensing robotis adjusted in accordance with the distance from the base station, andefficient searching of an object becomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, the plurality of fluttering sensing robots mayconsist of a plurality of groups in accordance with the distance fromthe base station, and frequency of fluttering motion of the plurality offluttering sensing robots may be controlled such that the frequency ofthe fluttering sensing robots in a group close to a base station issmaller than that of the fluttering sensing robots of a group far fromthe base station.

In accordance with the above described configuration, the flutteringfrequency of fluttering motion of each of the fluttering sensing robotis made smaller in a group closer to the base station, and efficientsearching of an object becomes possible.

In the group robot system in accordance with the first aspect of thepresent invention, the frequency of fluttering motion of the pluralityof fluttering sensing robots may be controlled such that the frequencyof the fluttering sensing robot closer to a base station is smaller thanthat of the robot far from the base station.

In accordance with the above described configuration, the flutteringfrequency of fluttering motion of the fluttering sensing robot closer tothe base station is made smaller, and efficient searching of an objectbecomes possible.

The sensing robot in accordance with the first aspect of the presentinvention searches for an object under the control of a base station,and when a plurality of sensing robots searches for an object, themanner related to search for an object of the plurality of sensing robotcan be controlled such that the manner differ from each other, inaccordance with the distance from the base station.

By such a configuration, the plurality of sensing robots are controlledsuch that the manner related to searching for an object differ inaccordance with the distance from the base station, and efficientsearching of the object becomes possible.

The base station in accordance with the first aspect of the presentinvention controls the plurality of sensing robots searching for anobject, and it is capable of controlling the plurality of sensing robotssuch that the manner related to searching for the object of theplurality of sensing robots differ from each other, in accordance withthe distance from the base station.

By the above described configuration, a plurality of sensing robots arecontrolled such that the manner related to searching of the objectdiffer in accordance with the distance from the base station, andefficient searching of the object becomes possible.

According to a second aspect, the present invention provides a grouprobot system including a plurality of sensing robots used for searchingfor an object, and a base station for controlling the plurality ofsensing robots, wherein a communication system of the group robot systemhas a hierarchical structure in which the base station is the highestlayer and the plurality of sensing robots constitute a plurality oflayers, and in the hierarchical structure, information related tocontrol of each of the plurality of sensing robots is transmitted fromthe base station to each of the plurality of sensing robots successivelyto the lower side of the hierarchical structure, and from each of theplurality of sensing robots, information related to searching of theobject of each of the plurality of sensing robots is transmitted to thebase station successively upward through the hierarchical structure, sothat the sensing robots are controlled such that the manner related tosearching of the object differ in accordance with the layer of thehierarchical structure.

By the above described configuration, the plurality of sensing robotsare controlled such that the manner related to searching of the objectdiffer in accordance with the layer of the hierarchical structure, andefficient searching of the object becomes possible. Further, ascommunication takes place in the hierarchical structure, the distance ofcommunication between each of the sensing robots or between the basestation and the sensing robots can be made shorter as compared with theone-to-one communication between the base station and the sensing robot.Therefore, the scope of search while the base station is in a stationarystate can be made wider, while reducing the size or weight of thecommunication mechanism of each sensing robot.

In the group robot system in accordance with the second aspect of thepresent invention, the manner related to searching of the object may besensing resolution of the sensing robot.

By the above described configuration, as the sensing resolution of eachof the plurality of sensing robots is adjusted in accordance with thelayer of the hierarchical structure, efficient searching of the objectbecomes possible.

In the group system in accordance with the second aspect of the presentinvention, the plurality of sensing robots may consist of a plurality ofgroups in accordance with the layer of the hierarchical structure, andthe sensing resolution of the plurality of sensing robots may becontrolled such that the sensing robots of a group of a higher layer ofthe hierarchical structure has higher resolution than the sensing robotsin the group of the lower layer of the hierarchical structure.

By the above described configuration, the sensing resolution of each ofthe plurality of sensing robots is set such that the resolution ishigher in a group of a higher layer of the hierarchical structure, andefficient searching of an object becomes possible.

In the group robot system in accordance with the second aspect of thepresent invention, the sensing resolution of the plurality of sensingrobots may be controlled such that a sensing robot of a higher layer ofthe hierarchical structure has higher resolution than a sensing robot oflower layer of the hierarchical structure.

By the above described configuration, the sensing resolution of each ofthe plurality of sensing robots is set such that a sensing robotbelonging to a higher layer of the hierarchical structure has higherresolution, and efficient searching of an object becomes possible.

In the group robot system in accordance with the second aspect of thepresent invention, the manner related to searching of an object may bethe speed of movement of the sensing robot.

By such a configuration, as the speed of movement of each of theplurality of sensing robots is adjusted in accordance with the layer ofthe hierarchical structure, efficient searching of an object becomespossible.

In the group robot system in accordance with the second aspect of thepresent invention, the plurality of sensing robots consist of aplurality of groups in accordance with respective layers of ahierarchical structure, and the speed of movement of the plurality ofsensing robots may be controlled such that a sensing robot of a group ofa higher layer of the hierarchical structure is slower than the sensingrobot of a group of a lower layer of the hierarchical structure.

By the above described configuration, as the speed of movement of eachof the plurality of sensing robots is made such that the speed is slowerin the group belonging to a higher layer of the hierarchical structure,efficient searching of an object becomes possible.

In the group robot system in accordance with the second aspect of thepresent invention, the speed of movement of the plurality of sensingrobots may be controlled such that a sensing robot of a higher layer ofthe hierarchical structure is slower than the sensing robot of a lowerlayer of the hierarchical structure.

By the above described configuration, as the speed of movement of eachof the plurality of sensing robots is made such that the speed of asensing robot in the group belonging to a higher layer of thehierarchical structure is slower, efficient searching of an objectbecomes possible.

In the group robot system in accordance with the second aspect of thepresent invention, the sensing robot is a fluttering sensing robot thatcan fly through fluttering motion, and the manner of searching for anobject may be the frequency of fluttering motion of the plurality offluttering sensing robots.

By the above described configuration, the frequency of fluttering motionof each of the plurality of fluttering sensing robots is adjusted inaccordance with the layer of the hierarchical structure, and efficientsearching of an object becomes possible.

In the group robot system in accordance with the second aspect of thepresent invention, the plurality of fluttering sensing robots mayconsist of a plurality of groups in accordance with the layer ofhierarchical structure, and frequency of fluttering motion of theplurality of fluttering sensing robots may be controlled such that afluttering sensing robot of a group of a higher layer of thehierarchical structure has smaller frequency than the fluttering sensingrobot of a group of a lower layer of the hierarchical structure.

By the above described configuration, the frequency of fluttering motionof each of the plurality of fluttering sensing robots is made smaller ina group belonging to a higher layer of the hierarchical structure, andefficient searching of an object becomes possible.

In the group robot system in accordance with the second aspect of thepresent invention, the frequency of fluttering motion of the pluralityof fluttering sensing robots may be controlled such that a flutteringsensing robot of a higher layer of the hierarchical structure hassmaller frequency than a fluttering sensing robot of a lower layer ofthe hierarchical structure.

By the above described configuration, the frequency of fluttering motionof each of the plurality of fluttering sensing robots of a higher layerof the hierarchical structure is made smaller, and efficient searchingof an object becomes possible.

The sensing robot in accordance with the second aspect of the presentinvention searches for an object under control of a base station, andused in a group robot system in which a communication system is set as ahierarchical structure in which the base station is the uppermost layerand the plurality of sensing robots constitute a plurality of layers,and the robot has a function of transmitting information related tosearching of the object of the sensing robot belonging to layer lowerthan itself to a higher layer of the hierarchical structure, and thefunction of transmitting information related to an operation of asensing robot belonging to a layer lower than itself, to a layer lowerby one, of the hierarchical structure, and when an object is searched,manner related to searching of an object among the plurality of sensingrobot can be controlled by the base station such that the manner differfrom each other in accordance with the layer of the hierarchicalstructure.

By the above described configuration, the plurality of sensing robotsare controlled such that the manner related to searching of the objectdiffer in accordance with the layer of the hierarchical structure, andefficient searching of the object becomes possible. Further, ascommunication takes place in the hierarchical structure, the distance ofcommunication between each of the sensing robots or between the basestation and the sensing robots can be made shorter as compared with theone-to-one communication between the base station and the sensing robot.Therefore, the scope of search while the base station is in a stationarystate can be made wider, while reducing the size or weight of thecommunication mechanism of each sensing robot.

The base station in accordance with the second aspect of the presentinvention controls a plurality of sensing robots so that the robotssearch for an object, used in a group robot system in which acommunication system of the group robot system has a hierarchicalstructure in which the base station is the highest layer and theplurality of sensing robots constitute a plurality of layers, and in thehierarchical structure, information related to control of each of theplurality of sensing robots is transmitted from the base station to eachof the plurality of sensing robots successively to the lower side of thehierarchical structure, and from each of the plurality of sensingrobots, information related to searching of the object of each of theplurality of sensing robots is transmitted to the base stationsuccessively upward through the hierarchical structure, and the basestation can control the plurality of sensing robots such that the mannerrelated to searching of the object differ in accordance with the layerof the hierarchical structure.

By the above described configuration, the plurality of sensing robotsare controlled such that the manner related to searching of the objectdiffer in accordance with the layer of the hierarchical structure, andefficient searching of the object becomes possible. Further, ascommunication takes place in the hierarchical structure, the distance ofcommunication between each of the sensing robots or between the basestation and the sensing robots can be made shorter as compared with theone-to-one communication between the base station and the sensing robot.Therefore, the scope of search while the base station is in a stationarystate can be made wider, while reducing the size or weight of thecommunication mechanism of each sensing robot.

According to the third aspect, the present invention provides a grouprobot system including a sensing robot used for searching of an object,and a base station for controlling the sensing robot, in which thesensing robot is controlled such that the manner related to searching ofan object is changed in accordance with the stage of searching of theobject.

By the above described configuration, the manner related to searching ofan object of the sensing robot is changed in accordance with the stageof searching for the object, and efficient searching of an objectbecomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, the manner related to the search of the object may besensing resolution of the sensing robot.

By the above described configuration, the sensing resolution of thesensing robot is changed in accordance with the stage of searching ofthe object, and efficient searching of an object becomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, the manner related to searching of an object may bethe type of a detection sensor of the sensing robot, or a method ofprocessing sensor information.

By the above described configuration, the type of the detection sensoror the sensor information of the sensing robot is changed in accordancewith the stage of searching of the object, and efficient searching of anobject becomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, the aforementioned stage of searching of the objectmay be the stage of detection of the object by the sensing robot.

By the above described configuration, when the sensing robot detects theobject, the manner related to searching of the object is changed, andtherefore, after the sensing robot detects the object, efficientsearching of the object becomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, among the plurality of sensing robots, the mannerrelated to searching of an object of that sensing robot which hasdetected the object may be changed.

By the above described configuration, the manner related to searching ofan object of the sensing robot that has detected the object is changed,and therefore, efficient searching of an object becomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, among the plurality of sensing robots, the mannerrelated to the searching of the object of those sensing robots that arepositioned around the sensing robot that has detected the object may bechanged.

By this configuration, as the manner of search of an object of thesensing robot that has detected the object is changed, and efficientsearching of the object becomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, the stage of searching of the object may be the stagewhere the sensing robot cease to detect the object.

By the above described configuration, the manner related to searching ofthe sensing robot is changed when detection of an object is stopped, andtherefore, after detection of the object is stopped, efficient searchingof the object becomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, among a plurality of sensing robots, the mannerrelated to searching of an object of that sensing robot which ceases todetect the object may be changed.

By the above described configuration, the manner related to searching ofan object of the sensing robot that ceases to detect the object ischanged, and therefore, after detection of the object is stopped,efficient searching of the object becomes possible.

In the group robot system in accordance with the third aspect of thepresent invention, among the plurality of sensing robots, the mannerrelated to searching of an object of sensing robot positioned in aregion around the sensing robot that ceases to detect the objects may bechanged.

By the above described configuration, the manner related to searching ofan object of sensing robot positioned in the region around the sensingrobot that ceases to detect the object is changed, and efficientsearching of an object becomes possible.

According to the third aspect of the present invention, the sensingrobot searches for an object under the control of a base station, andthe sensing robot is controlled such that the manner related tosearching of an object of the sensing robot is changed by the basestation in accordance with the stage of searching of the object.

By the above described configuration, the manner related to searching ofan object of the sensing robot is changed in accordance with the stageof the search of the object, and efficient searching of an objectbecomes possible.

According to the third aspect of the present invention, the base stationcontrols a plurality of sensing robots searching for an object, andcontrols the sensing robots such that the manner related to searching ofan object by the sensing robot change in accordance with the stage ofsearching of the object.

By the above described configuration, the manner related to searching ofan object of the sensing robot is changed in accordance with the stageof searching of the object, and efficient searching of an object becomespossible.

According to a fourth aspect, the present invention provides a grouprobot system including a plurality of sensing robots used for searchingfor an object, and a base station for controlling the plurality ofsensing robots, wherein the plurality of sensing robots search for anobject, moving along with the movement of the base station, whilemaintaining a tolerable range of positional relation with the basestation.

By such a configuration, the plurality of sensing robots search for anobject while moving along with movement of the base station, withtolerable range of positional relation with the base station beingmaintained, and therefore, efficient searching of an object becomespossible.

In the group robot system in accordance with the fourth aspect of thepresent invention, preferably, the plurality of sensing robots movewhile maintaining tolerable range of positional relation with eachother.

By the above described configuration, the plurality of sensing robotsmove while maintaining tolerable range of positional relation with eachother, and therefore, more efficient searching of an object becomespossible.

In the group robot system in accordance with the fourth aspect of thepresent invention, preferably, the plurality of sensing robots are setto move in such an arrangement in that the base station is positioned atthe center of concentric circles, when the plurality of sensing robotsare arranged concentrically.

By the above described configuration, the plurality of sensing robotsmove arranged in such a state in that the base station is positioned atthe center of concentric circles with the plurality of sensing robotsarranged concentrically, and therefore, more efficient searching of anobject becomes possible.

In the group robot system in accordance with the fourth aspect of thepresent invention, preferably, the base station is set to move toward anobject, when a sensing robot detects the object.

By the above described configuration, when a sensing robot detects anobject, the base station moves toward the object, and hence moreefficient searching of an object becomes possible.

In the group robot system in accordance with the fourth aspect of thepresent invention, preferably, the base station moves such that there isno gap and no overlap between the search area of each of the pluralityof sensing robots.

By the above described configuration, the base station moves such thatthere is no gap and no overlap generated between search areas of theplurality of sensing robots, and therefore, more efficient searching ofan object becomes possible.

In the fourth aspect, the sensing robots search for an object under thecontrol of the base station, and when an object is searched by aplurality of sensing robots, the robots are controlled by the basestation such that the robots move along with the movement of the basestation while searching for the object, maintaining a tolerable range ofpositional relation with the base station.

By the above described configuration, the plurality of sensing robotsmove along with the movement of the base station, searching for anobject, while maintaining a tolerable range of positional relation withthe base station, and therefore, efficient searching of an objectbecomes possible.

According to the fourth aspect of the present invention, the basestation controls a plurality of sensing robots used for searching for anobject, and controls the plurality of sensing robots such that therobots move along with the movement of the base station whilemaintaining a tolerable range of positional relation with the basestation, searching for the object.

By the above described configuration, the plurality of sensing robotsmove along with the movement of the base station, to search for anobject, while maintaining a tolerable range of positional relation withthe base station, and therefore, efficient searching of an objectbecomes possible.

According to a fifth aspect, the present invention provides a grouprobot system including a plurality of sensing robots used for searchingfor an object, and a base station for controlling the plurality ofsensing robots, wherein the plurality of sensing robots are controlledsuch that the manner related to searching of the object of each of theplurality of sensing robots is independent from each other.

By the above described configuration, the manner related to searching ofthe object of each of the plurality of sensing robots can be controlledindependently, and efficient searching of an object becomes possible.

In the group robot system in accordance with the fifth aspect of thepresent invention, when the manner related to searching of an object ofeach of the plurality of sensing robots is controlled independently, themanner related to searching of the object of each of the plurality ofsensing robots may be controlled to be a in different fixed state,dependent on the environment.

By the above described configuration, the manner related to searching ofan object of each of the plurality of sensing robots is controlled suchthat the manner is fixed differently in accordance with the environment,and efficient searching of an object becomes possible.

The sensing robot in accordance with the fifth aspect of the presentinvention is used for searching for an object under the control of abase station, and when a plurality of sensing robots are used forsearching for an object, the manner related to searching of the objectis controlled independently from other sensing robots.

By the above described configuration, as the manner of searching of theobject is controlled independently for each of the plurality of sensingrobots, efficient searching of an object becomes possible.

The base station in accordance with the fifth aspect of the presentinvention controls a plurality of sensing robots used for searching foran object, and it is capable of controlling, when a plurality of sensingrobots search for the object, the manner related to searching of theobject of each of the plurality of sensing robots independently.

By the above described configuration, the manner related to searching ofan object of each of the plurality of sensing robots can be controlledindependently, and efficient searching of an object becomes possible.

A program for operating the above described sensing robot or the basestation is executed by a computer, and the sensing robot or the basestation functions in the group robot system. The program may be recordedon a recording medium such as a CD-ROM and read by the sensing robot, orit may be installed from an information network such as the Internet andread by the robot.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the group robot system in accordance with an embodiment ofthe invention.

FIG. 2 represents relation between fluttering frequency and position offluttering sensing robots in the group robot system of the presentembodiment.

FIG. 3 represents relation between magnitude of resolution and positionof fluttering sensing robots of the group robot system in accordancewith the present embodiment.

FIGS. 4 to 6 represent relation between time-change in sensingresolution and position, before and after detection of an object by afluttering sensing robot of the group robot system in accordance withthe present embodiment.

FIGS. 7 to 9 represent relation between change in selected sensor andhierarchical structure of communication, before and after detection ofthe object by a fluttering sensing robot of the group robot system inaccordance with the present embodiment.

FIGS. 10 to 12 represent relation between change in selected sensor andhierarchical structure of communication, before and after detection ofthe object by a fluttering sensing robot of the group robot system inaccordance with the present embodiment.

FIG. 13 is an illustration of the hierarchical structure of thecommunication system in the group robot system in accordance with thepresent embodiment.

FIG. 14 is an illustration representing tree structure of thecommunication system of the group robot system in accordance with thepresent embodiment.

FIGS. 15 and 16 represent flow of control signals for the flutteringsensing robot of the group robot system in accordance with the presentembodiment.

FIG. 17 shows a delay profile of the control signal in spread spectrumcommunication of the group robot system in accordance with the presentembodiment.

FIG. 18 is an illustration schematically representing an example ofcommunication relation between the fluttering sensing robot and the basestation in accordance with an embodiment of the invention.

FIG. 19 is a front view showing a structure of the fluttering sensingrobot in accordance with an embodiment of the invention.

FIG. 20 is an enlarged perspective view showing the wing of thefluttering sensing robot in accordance with an embodiment.

FIG. 21 represents a stroke angle θ and a declination α of the wing ofthe fluttering sensing robot in accordance with an embodiment.

FIG. 22 represents a torsion angle β of the wing of the flutteringsensing robot in accordance with an embodiment.

FIGS. 23 to 25 are illustrations of a stator portion of an actuator usedfor fluttering of the fluttering sensing robot in accordance with anembodiment.

FIGS. 26 and 27 are illustrations of the actuator formed by using thestator for fluttering of the fluttering sensing robot in accordance withan embodiment.

FIG. 28 represents a down stroke of the fluttering operation of thefluttering sensing robot of an embodiment.

FIG. 29 represents an up stroke of the fluttering operation of thefluttering sensing robot in accordance with an embodiment.

FIGS. 30 to 33 show the first to fourth states of the flutteringoperation of the fluttering sensing robot in accordance with anembodiment.

FIG. 34 is a first graph showing time dependency of the wing drive inthe fluttering operation of the fluttering sensing robot in accordancewith an embodiment.

FIG. 35 is a second graph representing time dependency of wing drive ofthe fluttering operation of the fluttering sensing robot in accordancewith an embodiment.

FIG. 36 is a graph showing result of simulation of actuator torque andsupporting reaction when the wing of the fluttering sensing robot of theembodiment is driven.

FIG. 37 is an illustration of the base station controlling thefluttering sensing robot in accordance with an embodiment.

FIG. 38 is an illustration representing relation between the flutteringsensing robot and the base station in accordance with an embodiment.

FIG. 39 is a flow chart representing an example of operation of thefluttering sensing robot system in accordance with an embodiment.

FIG. 40 is a flow chart representing information processing in theprocess of take off of the fluttering sensing robot in accordance withan embodiment.

FIG. 41 is a flow chart representing information processing in thepatrol process of the fluttering sensing robot in accordance with anembodiment.

FIG. 42 is a flow chart representing information processing in thelanding process of the fluttering sensing robot in accordance with anembodiment.

FIG. 43 is an illustration of the fluttering sensing robot in accordancewith another embodiment, including a partial front view on the leftside, and a partial side view on the right side.

FIG. 44 is a graph representing a relation between beating motion and aphase of the beating motion, in said another embodiment.

FIGS. 45 to 52 are illustrations showing the first to eighth states offluttering operation of the fluttering sensing robot in accordance withanother embodiment.

FIG. 53 is a schematic front view showing the fluttering sensing robotin accordance with a modification of said another embodiment.

FIG. 54 is a schematic front view showing the fluttering sensing robotin accordance with another modification of said another embodiment.

FIG. 55 is a schematic front view showing the fluttering sensing robotin accordance with a still further modification.

FIG. 56 is a schematic plan view showing a structure of the flutteringsensing robot in accordance with said another embodiment.

FIG. 57 is a first graph representing changes in force acting on thewing and the angle with respect to the beating phase, respectively, insaid another embodiment.

FIG. 58 is a second graph representing changes in the force acting onthe wing and the angle with respect to the beating phase, in accordancewith said another embodiment.

FIG. 59 is an illustration representing control functions for flutteringflight control.

FIG. 60 is a table representing correspondence between change in themanner of fluttering of a left wing and the resulting change in thestate of flight.

FIG. 61 is a table representing combinations of patterns of the mannerof fluttering to realize basic operations of fluttering flight.

FIG. 62 represents a conventional system for recognizing environment,having a plurality of sensors with the information processing mechanismof the sensors being hierarchical.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The group robot system including sensing robots and a base station inaccordance with an embodiment will be described with reference to FIGS.1 to 17. In the present embodiment, by way of example, a group robotsystem will be described, which searches for a heat source such as afire or a person, searches for toxic gas such as CO or toxic radiation,searching for metal such as land mine, or collects three-dimensionalimage data for collecting VR data for urban planning within an area ofas small as several meters square up to as large as several kilometerssquare.

According to the present embodiment, when toxic gas is to be searchedfor in a whole town, the group robot system do not search for the gasover all the urban areas at one time, but a group of fluttering sensingrobots for searching with a base station placed at the center ofconcentrical circles searches for the object in each of a number ofdivided areas of the town. When the group of fluttering sensing robotsfinishes searching of the toxic gas or toxic radiation of one of thedivided areas of the town mentioned above, the base station starts freemovement to start searching in the next one of the divided areas of thetown, and the base station stops when it reaches the target area of thetown.

Following the movement of the base station, pheromone robots and sensingrobots start movement. When the base station stops its movement in thenext area of the town, the group of sensing robots searches for thetoxic gas or the toxic radiation of the divided area of the town, withthe base station being the center of concentric circles. In this manner,according to the present embodiment, the group of a plurality of sensingrobots search in a divided area transmits the result of searching to thebase station and when searching of an area is completed, the group ofrobots moves with the base station being the center, and searches in thenext area. By repeating this operation of movement, the whole area issearched. At this time, when the group of fluttering sensing robotsmoves such that there is no gap or overlapping between the scope ofsearch of each of the plurality of fluttering sensing robots, efficientsearching becomes possible.

The group robot system in accordance with the present embodiment will bedescribed with reference to FIGS. 1 to 22. The group robot system 100used for the present embodiment consists of a base station BS, aplurality of fluttering sensing robots CS, and a plurality of flutteringpheromone robots FE, as shown in FIG. 1.

FIG. 1 is a schematic illustration of the overall image of the robotgroup. FIG. 7 shows relation between the position and hierarchicalstructure in communication between each of the sensing robots CS andbetween the sensing robot CS and the base station BS in the group robotsystem. In the present embodiment, the plurality of fluttering sensingrobots CS is divided into three groups, that is, a group 102 (CS11 toCS1i) closest to the base station BS, a group 103 (CS21 to CS2j) secondclosest to the base station, and a group 104 (CS31 to CS3k) farthestfrom the base station. Though the robots are divided into three groupsin the present embodiment, the number of groups is not limited to three,and what is necessary is that there is a plurality of groups.

FIG. 2 shows relation between position and fluttering frequency fvbetween each of the sensing robots CS and between each sensing robot CSand the base station BS, of the group robot system.

The distance of movement per unit time of a fluttering sensing robot 104(CS31 to CS3k) farthest from the base station BS is larger than that ofthe sensing robot 103 (CS21 to CS2j) that are second farthest. In otherwords, fluttering frequency fv104 of fluttering sensing robot 104 (CS31to CS3k) is larger than fluttering frequency fv103 of fluttering sensingrobot 103 (CS21 to CS2j).

Similarly, the distance of movement per unit time of sensing robot 103(CS21 to CS2j) is larger than that of sensing robot 102 (CS11 to CS1i)closest to the base station BS. In other words, fluttering frequencyfv103 of fluttering sensing robot 103 (CS21 to CS2j) is larger thanfluttering frequency fv102 of fluttering sensing robot 102 (CS11 toCS1i).

Therefore, in the present embodiment, sensing robots CS of lower layerhaving larger fluttering frequency, that is, the sensing robotsbelonging to the layer farther from the base station, move faster andhave lower resolution.

FIG. 3 represents relation between position and sensing resolution Rbetween each of the sensing robots CS and between the sensing robot CSand the base station BS of the group robot system.

Assume that sensor accuracy and sampling rate are the same among allsensing robots CS. From the relation between the position of the robotsand the distance of movement per unit time described above, the sensingresolution is as follows. Namely, spatial resolution R104 for detectingan object of sensing robot 104 (CS31 to CSk) farthest from base stationBS101 is lower than resolution R103 for detecting an object offluttering sensing robot 103 (CS21 to CS2j) that is the second farthestfrom base station. Specifically, fluttering sensing robot 104 (CS31 toCS3k) farthest from the base station BS101 has lower accuracy ofposition detection for detecting the object, or lower precision ofmeasurements of the size of an obstacle, as compared with flutteringsensing robot 103 (CS21 to CS2j) that is the second farthest.

Similarly, assuming that sensor accuracy and sampling rate are the sameamong all sensing robots, because of the relation between the positionof the robots and the distance of movement per unit time describedabove, the spatial resolution R103 for detecting an object of flutteringsensing robot 103 (CS21 to CS2j) is lower than spatial resolution R102for detecting an object of fluttering sensing robot 102 (CS11 to CS1i)that is closest to the base station BS101. Specifically, sensing robot103 (CS21 to CS2j) has lower accuracy of position detection fordetecting an object and lower precision of measurements of the size ofthe obstacle, as compared with fluttering sensing robot 102 (CS11 toCS1i) that is closest to the base station BS101.

In the example above, spatial resolution is different because of thedifference in distance of movement per unit time (speed of movement),with the sampling rate being the same. When all the fluttering sensingrobots move approximately at the same speed, the spatial resolution maybe made different by changing sampling rate.

When a sensing robot CS detects an object, presence/absence of theobject, position information and the like are transmitted to basestation BS101 through a method which will be described later. Based onthe transmitted information, base station BS101 starts free movementtoward the object. As base station BS101 moves, sensing robots CSpositioned approximately concentrically also move toward the object. Asensing robot CS closer to base station BS, that is, the higher layer ofthe hierarchical structure, has higher spatial resolution. Therefore, asthe base station BS comes closer to the object, accuracy of positiondetection for detecting the object or sensing information related to thesize of an obstacle that is to be transmitted to base station BS,becomes higher.

Alternatively, the following approach may be possible. Namely, when asensing robot detects an object, the robot that has detected the objectcomes to have higher resolution, and at the same time, presence/absenceof the object, position information and the like are transmitted to basestation BS101 by the method which will be described later.

FIG. 4 shows an example of the relation between position and time-changesensing resolution R before and after detection of an object 106 betweeneach of the sensing robots CS and between the sensing robot CS and thebase station BS of the group robot system.

Before detection of the object, referring to FIG. 4, sensing resolutionof the sensing robot group is R104. When a sensing robot CS35 of theoutermost layer detects object 106, sensing resolution of sensing robotCS35 is changed to R102 (>R104) as shown in FIG. 5. More specifically,after detection of object 106, sensing robot CS35 that has detected theobject comes to have higher spatial resolution R by increasing samplingrate, or comes to have higher sensing resolution R by decreasingfluttering frequency so as to lower the speed of movement.

Thereafter, when an object detection signal indicating detection of anobject is transmitted to base station, the base station instructs allsensing robots CS to set spatial resolution higher by increasingsampling rate, or to increase resolution by decreasing flutteringfrequency so as to slower the speed of movement. Thus, sensingresolution R of all the sensing robots CS is changed to R102 (>R104) asshown in FIG. 6. At this time, sensing resolution R of only that sensingrobot CS35 that has detected the object may be set higher.

After detection of object 106, information of position detection of theobject or information related to the size of the obstacle that is ofhigher precision, is transmitted to the base station.

Alternatively, the sensing robot may utilize ultrasonic sensor orinfrared sensor until detection of the object, and when a sensing robotdetects the object, the sensing robot that has detected the object mayswitch the sensor type to a CCD (Charge Coupled Device) or to a CMOS(Complementary Metal Oxide Silicon) image sensor, so as to enabletransmission of more detailed image information of the object.

FIG. 7 shows an example of position and time-change of the sensorselected before and after detection of object 106 between each of thesensing robots CS and between the sensing robot CS and the base stationBS of the group robot system.

Before detecting an object, the sensor of the sensing robot group is aninfrared detection sensor as shown in FIG. 7. Then, when a sensing robotCS35 the outermost layer detects object 106, sensing robot CS35 switchesthe sensor from the infrared detection sensor to a CMOS image sensor, asshown in FIG. 8.

Thereafter, presence/absence of the object detected by sensing robotCS35, position information and the like are transmitted to base stationBS101 by the method, which will be described later, and the sensor typeof sensing robots CS34 and CS36 around the object 106 governed by asensing robot CS25 of higher layer to which sensing robot CS35 that hasdetected the object belongs, is switched from the infrared detectionsensor to the CMOS image sensor (or CCD). In this manner, it becomespossible to transmit detailed overall image of the object efficiently ina short time.

Alternatively, another approach may be adapted as shown in FIGS. 10 to12, in which, before detecting an object, the sensor of the sensingrobot group is an infrared detection sensor as shown in FIG. 10. When asensing robot CS35 of the outermost layer detects object 106, the sensorof sensing robot CS35 is changed from the infrared detection sensor to aCMOS image sensor as shown in FIG. 11.

Thereafter, presence/absence of the object detected by sensing robot CS,position information and the like are transmitted to base station BS101by the method which will be described later, and then, the type of thesensor of sensing robots CS34, CS36 and the like around the object 106which are governed by sensing robot CS25 of the higher layer to whichsensing robot CS35 that has detected the object belongs, is switchedfrom the infrared detection sensor to a sensor that is different fromthe CMOS image sensor (or a CCD) used in the sensing robot CS35. Forexample, sensor of sensing robot CS34 may be switched to a toxic gassensor for detecting CO, and the sensor of sensing robot CS36 may beswitched to a sensor for detecting toxic radiation. By such an approach,detailed overall information of the object can be obtained efficientlyin a short time.

Alternatively, the sensing robot may perform image processing of edgedetection, until the object is detected, and when a sensing robotdetects the object, image processing of the sensing robot that hasdetected the object may be changed to color detection processing.Namely, the sensor hardware is the same while the method of processingsensor information is changed after detection of the object.

Alternatively, even when a sensing robot detects an object, spatialresolution of the sensing robots, sensor type and the method of imageprocessing may not be changed until scanning of a predetermined area bythe group of robots is completed, and when scanning of the predeterminedarea is completed and there is a detection signal, the same area may besubjected to detection operation again, to find different information ofthe object, with different sensor spatial resolution, different sensortype or different method of image processing, by the group of sensingrobots.

In such a group robot system of the embodiment as described above, whena large number of fluttering sensing robots detect an object whilemoving, the burden caused by processing of sensor information can bereduced, and as the robots move closer to the object of searching,accuracy of position detection of the object, or accuracy of sensinginformation related to the magnitude of obstacle, for example, can beset higher after the object is detected.

Even when the fluttering sensing robot group does not move, the burdencaused by the processing of sensor information can be reduced and afterdetection of the object, information related to the position detectionof the object or the magnitude of obstacle with higher accuracy can beobtained. Further, it is not the case that sensors of all the flutteringsensing robots operate constantly, and therefore, power consumption canbe reduced.

When the sensor is switched to one having higher sensitivity upondetection of an object, it becomes possible to obtain detailed overallinformation of the object efficiently in a short time. Further, when thesensor type and the method of processing are changed upon detection ofthe object, information of different target values can be detected,again efficiently.

In the above described embodiment, examples have been described in whichsensing resolution, speed of movement and fluttering frequency offluttering sensing robots CS differ layer by layer. The effect thatoverall information of the object can be grasped efficiently can also beobtained in a group robot system in which sensing resolution, speed ofmovement and fluttering frequency differ group by group of the unit oftwo layers or three layers in a hierarchical structure including aplurality of layers.

Though an example of a group robot system having a hierarchicalstructure has been described in the embodiment above, the effect thatoverall information of the object can be grasped efficiently can also beobtained even when the plurality of fluttering sensing robots CS do notform a hierarchical structure that have different sensing resolution,speed of movement and fluttering frequency in accordance with thedistance from the base station. Here, each of the fluttering sensingrobots may have different sensing resolution, different speed ofmovement and different fluttering frequency, in accordance with distancefrom the base station. When sensing resolution is set to be highercloser to the base station and speed of movement and the flutteringfrequency set to be lower closer to the base station, it becomespossible to obtain detailed overall information of the object thatgradually increasing accuracy, as the base station comes closer to theobject.

A group robot system of which sensing resolution becomes higher and thespeed of movement and frequency becomes lower in the higher layer ofhierarchical structure, that is, closer to the base station, has beendescribed as an example of the embodiment. Alternatively, in the grouprobot system, sensing resolution may be set higher and the speed ofmovement and frequency are set lower in sensing robots CS of the lowerlayer of the hierarchical structure. In that case, as the sensingresolution of the lowermost layer is high until an object of searchingis found, the possibility of failure to find the object of searching canbe reduced. Further, when sensing by the sensing robots belonging to thehigher layer of the hierarchical structure is stopped, burden incontrolling and power consumption of the sensing robots CS of the higherlayer and of the base station BS can be reduced.

Further, such an approach may also be possible in which when a sensingrobot CS detects an object of searching, sensing resolution of only thesensing robot CS that detected the object and the sensing robotsexisting in the area around that sensing robot CS is set higher thanothers. Alternatively, when a sensing robot CS ceases to detect theobject of searching, sensing resolution of that sensing robot CS may beset lower, and the sensing resolution of only the sensing robots CSexisting in the area around that sensing robot CS may be set higher thanothers. Consequently, burden in control and power consumption of basestation BS and sensing robots CS can be reduced. Even in a group robotsystem in which sensing robots CS that perform sensing change with time,burden in control and power consumption of the base station BS and thesensing robots CS may be reduced.

In summary, in the group robot system of the embodiment described above,the manner of detection of the object including speed of movement,frequency of fluttering motion and sensing resolution of each of theplurality of sensing robots can be controlled by the base station,independently for each of the sensing robot CS. Therefore, as comparedwith the conventional sensing robots in which the manner of detection ofthe object cannot be controlled independently, efficient searching ofthe object becomes possible.

Further, independent control of each of the sensing robots CS may besuch that a specific sensing robot CS among the plurality of sensingrobots CS performs operations until an object is detected, and when theobject is detected, other sensing robots CS move to the position of theobject to grasp detailed overall information. Namely, the control of thesensing robots CS may be fixed such that each robot can performsearching in its own manner of searching different from other robots.

Referring to FIGS. 1 to 14, communication between the base station BS101and the plurality of sensing robots is implemented in a hierarchicalstructure. Base station 101 communicates with sensing robot 102 (CS11 toCS1i) of the group closest to the base station BS on the concentricalcircles. From base station BS in the up stream, changes of flutteringsuch as the frequency or direction of fluttering, are transmitted tofluttering sensing robot 102 (CS11 to CS1i). From fluttering sensingrobot 102 (CS11 to CS1i) of the down stream, presence/absence of theobject, position information and the like are transmitted to basestation BS.

Then, sensing robot 102 communicates with sensing robot 103 (CS21 toCS2j) of the neighboring group. From sensing robot 102 (CS11 to CS1i) inthe up stream, changes of fluttering including frequency and directionof fluttering for a sensing robot 103 (CS21 to CS2j) that have beentransmitted from the base station BS101 to sensing robot 102 (CS11 toCS1i) are transmitted to fluttering sensing robot 103 (CS21 to CS2j).From fluttering sensing robot 103 (CS21 to CS2j) in the down stream,presence/absence of the object, position information and the like aretransmitted to sensing robot 102 (CS11 to CS1i).

Then, sensing robot 103 (CS21 to CS2j) communicates with sensing robot104 (CS31 to CS3k) of the neighboring group. From sensing robot 103(CS21 to CS2j) in the up stream, changes of fluttering includingfrequency and direction of fluttering for sensing robot 104 (CS31 toCS3k) that has been transmitted from base station BS101 through sensingrobot 102 (CS11 to CS1i) to sensing robot 103 (CS21 to CS2j) aretransmitted to fluttering sensing robot 104 (CS31 to CS3k).

Sensing robot 104 (CS31 to CS3k) in the down stream transmitspresence/absence of the object, position information and the like tosensing robot 103 (CS21 to CS2j) in the up stream. Specifically, when anobject is detected by fluttering sensing robot searching area CS31,detection signal is transmitted to sensing robot CS20 of the upperlayer, and from sensing robot CS20, transmitted further to sensing robotCS11 of the higher layer. Finally, detection of the object istransmitted from sensing robot CS11 to base station BS.

It is unnecessary for base station BS to cover all the communicationareas of all the fluttering robots. It may simply have communicationintensity that can secure communication with the group closest to thebase station of the surrounding concentrical circles. Therefore,communication intensity weaker than that ensures communication with allthe sensing robots is sufficient, and hence power consumption forcommunication can be reduced.

When communication intensity between fluttering sensing robot CS11 andbase station BS becomes lower than a predetermined level, the flutteringsensing robot moves toward the base station until the communicationintensity again exceeds the predetermined level. The same applies whenfluttering sensing robot CS11 as a higher layer robot communicates withfluttering sensing robot 103 (CS21 to CS24) in the down stream.

Though the sensing robot of the down stream moves until sufficientcommunication intensity is obtained in the example above, whencommunication intensity becomes lower than the predetermined level, thesensing robot and the sensing robot of the higher layer both may havecommunication powers increased, so as to ensure communication intensitybetween the sensing robot of the higher layer and the sensing robotgoverned by the robot of the higher layer.

FIG. 13 represents relation between hierarchical structure and theposition of pheromone robots of the group robot system in accordancewith the present invention.

Sensing robot CS1i governed by base station BS exists in a circle (BC2)that represents scope of communication of the base station BS, with basestation BS being the center of the circle. Next, a sensing robot CS2jgoverned by sensing robot CS1i exists in a circle (C1) that representsscope of communication of sensing robot CS1i, with sensing robot CS iibeing the center of the circle.

Similarly, a sensing robot CS3k governed by sensing robot CS2j exists ina circle (C2) representing the scope of communication of sensing robotCS2j, with sensing robot CS2j being the center. It follows that in thecircle of communication governed by sensing robot CS2j, there are aplurality of sensing robots CS2k governed by CS2j.

When it is the case that sensing robot CS3k is the outermost sensingrobot CS, then sensing robot CS3k is also governed by a pheromone robotFE. Specifically, sensing robot CS3k exists in a circle (FC2)representing scope of communication of pheromone robot FE, with thepheromone robot being the center.

Communication intensity between pheromone robot FE and base station BSis higher than for other communications. The pheromone robot FEbasically exists in the outermost area of searching, when the basestation BS is at the center. Pheromone robot FE exist in a circle (BC1)representing scope of communication with high intensity between basestation BS and pheromone robot FE, with the base station BS being thecenter. The scope of communication from pheromone robot FE to basestation BS is elliptical with high directivity, as it is unnecessary tocover all the directions (FC1).

The pheromone robot group FE105 will be described. Pheromone robot groupFE105 is positioned outer than sensing robot group 100 with the basestation BS101 at the center, and the pheromone robot is used forcontrolling movement of sensing robots CS and for determining the scopeof searching. Specifically, sensing robot CS exists between base stationBS101 and pheromone robot FE105. The robot of higher layer with respectto pheromone robot FE105 is the base station BS101, and the robot of thelower layer is the sensing robot group 104 (CS31 to CS3k) positioned onthe outermost one of the concentrical circles with the base stationBS101 being the center.

In the present example, that means the sensing robot group 104 (CS31 toCS3k). Communication intensity between pheromone robot FE105 and sensingrobot 104 (CS31 to CS3k) in the down stream is the same as thecommunication intensity between base station BS and the sensing robot(CS11 to CS1i) and between each of the sensing robots CS. Communicationintensity between pheromone robot FE105 and base station BS101, however,is higher than the intensity of other communications.

In the group robot system of the present embodiment, it is preferredthat maximum distance of communication between pheromone robot FE andbase station BS is larger than the sum of the maximum distance forcommunication between base station BS and the sensing robot (CS11 toCS1i) of the highest layer of the hierarchical structure, the maximumdistance of communication between pheromone robot FE and the sensingrobot (CS31 to CS3k) of the lowermost layer of the hierarchicalstructure, and the maximum distance of communication between each of theplurality of sensing robots CS. By such setting, it becomes possible touse the sensing robots CS efficiently, by making full use of thecommunication distance of each of the sensing robots, with the possibledistance of communication from the base station BS to the sensing robot(CS31 to CS3k) of the lowermost layer of hierarchical structure istreated as linear distance.

Base station BS101 positions pheromone robot FEn on the outer diameterportion of the approximately concentrical search area with the basestation BS101 being the center, so as to determine the portion forsearching. Thereafter, in accordance with the number of layers in thehierarchical structure, the scope of concentrical layers is determined.Thereafter, it determines the scope of a cell (scope of searching byeach of the sensor robots belonging to one layer of the hierarchicalstructure) in accordance with the number of fluttering sensing robotsbelonging to one layer, and determines spatial resolution for searchingof the sensing robots. Finally, communication intensity between the basestation BS and each of the sensing robots (CS11 to CS1i), andcommunication intensity between each of the sensing robots CS aredetermined, in accordance with the difference in radius of concentricalcircles resulting from the difference in hierarchical structure, and thecell area of the cell defining the scope of searching by each of thesensing robots represented by the concentrical circles.

When the area of searching is to be changed, base station BS101 firstcommunicates with pheromone robot FE105 to notify distance and directionof movement of base station BS101. Thereafter, base station BS101transmits distance and direction of movement to sensing robot 102 (CS11to CS1i). Thus, as base station BS101 moves in the direction of thearrow in FIG. 1, the group robot system as a whole moves in thedirection of the arrow shown in FIG. 1.

More specifically, sensing robot 102 (CS11 to CS1i) that receives thesignal indicating movement of the group robot system as a whole frombase station BS transmits the distance and direction of movement tosensing robot 103 (CS21 to CS2j) of the lower layer, and thereafter, itmoves in the direction of the arrows of FIG. 1. Pheromone robot FE105transmits the distance and direction of movement to sensing robot 104(CS31 to CS3k) of the lowermost layer, and thereafter, moves in thedirection of the arrow shown in FIG. 1, similar to base station BS.

In this manner, when the space for searching is to be changed,information of movement is transmitted from base station BS to sensingrobot CS and from sensing robot CS of a higher layer to a sensing robotCS of a lower layer, substantially simultaneously with transmission ofthe information of movement from pheromone robot FE to sensing robot CS.

Pheromone robot 105 at the outermost position of the search areadirectly governs sensing robot 104 (CS31 to CS3k) of the outermost groupof the sensing robots (that is, lowermost layer of the hierarchicalstructure). Pheromone robot FE always keeps a sensing robot CS specifiedby a PN code in a communication zone.

For example, when communication intensity between pheromone robot FE105and a fluttering sensing robot CS3k under its surveillance becomes lowerthan a predetermined level, fluttering sensing robot CS3k moves towardpheromone robot FE105, until the communication intensity again exceedsthe predetermined level. Further, as pheromone robot 105 is undersurveillance of base station BS101, it is possible to control distancefrom base station BS utilizing synchronous delay of communication, so asto maintain a prescribed distance from the base station BS101constantly. As a result, it becomes possible to substantially constantlydetermine substantially similar search area for the whole group.

FIG. 14 shows signal flows in the communication system of thehierarchical structure.

In the figure, solid lines represent motion control signals (downstream) and detection signals (up stream), while dotted lines representpower signals.

Communication between a fluttering sensing robot and the base station,and communication between each of the fluttering sensing robots arebi-directional. A signal from up stream to down stream is a motioncontrol signal of the sensing robot such as fluttering frequency ordirection of the robot, or a control signal for sensor control. A signalfrom the down stream to the up stream is a detection signal ofpresence/absence of the object, position information or the like. Thechain relation in communication between a robot of the up stream thatcontrols and a robot in the down stream that is controlled is one tomultiple or one to one, and as a whole, the relation establishes acommunication route of a tree structure. Consequently, there is alwaysone communication route from the base station to each sensing robot CS,and therefore, confusion in the communication system is avoided.

Communication between base station BS and pheromone robot FE is alsobi-directional. The signal from base station BS to pheromone robot FE isa signal representing speed or direction of movement of the base stationBS. Based on this signal, pheromone robot FE determines speed anddirection of its movement, and transmits control signal of flutteringfrequency, direction or the like to sensing robot CS. The signal frompheromone robot FE to base station BS is for measuring reception power.

Base station BS receives the transmission signal from pheromone robotFE, and measures the power thereof, so as to indirectly estimate thedistance between base station BS and pheromone robot FE, and inaccordance with the magnitude of power, causes pheromone robot FE tomove closer, or intensifies transmission signal from base station BS topheromone robot FE. The relation of numbers between base station BS andpheromone robot FE may be one to multiple or one to one.

Communication between pheromone robot FE and fluttering sensing robot CSis also bi-directional. The signal from pheromone robot FE to thesensing robot CS is a motion control signal of sensing robot CS such asfluttering frequency or direction of the robot, or a control signal forsensor control. The signal from fluttering sensing robot CS to pheromonerobot FE is a signal for measuring reception power.

Pheromone robot FE receives the transmission signal from sensing robotCS and measures the power, so as to indirectly estimate distance betweenpheromone robot FE and sensing robot CS, and in accordance with themagnitude of the power, it causes sensing robot CS to come closer topheromone robot FE. The relation of numbers between pheromone robot FEand sensing robot CS may be one to multiple or one to one.

FIGS. 15 and 16 represent, as a flow, examples of the procedure ofmoving the group of robots, in the group robot system havinghierarchical structure.

First, flow of the motion control signal will be described withreference to FIG. 15. In the figure, solid lines in the lateraldirection represent flow of motion control signals, dotted linesrepresent flow of power signals, and vertical solid lines represent timedelay.

First, from base station BS to sensing robots CS11 and CS12, a motioncontrol signal for the sensing robot CS including fluttering frequencyor direction of fluttering sensing robot, or a control signal for sensorcontrol is transmitted. At the same time, from base station BS topheromone robot FE, speed and direction of movement of the base stationBS are transmitted. From pheromone robot FE to base station BS, a signalfor measuring power, for estimating distance between base station BS andpheromone robot FE, is transmitted.

Thereafter, sensing robot CS11 transmits to sensing robots CS20 andCS21, a motion control signal for the sensing robot including flutteringfrequency or direction of the fluttering sensing robot or a controlsignal from sensor control. Sensing robot CS12 transmits to sensingrobot CS22, a motion control signal for sensing robot CS includingfluttering frequency or direction of the robot, or a control signal forsensor control.

Pheromone robot FE1 transmits to sensing robots CS30 and CS31, a motioncontrol signal for sensing robot CS including fluttering frequency ordirection of fluttering sensing robot, or a control signal for sensorcontrol.

Pheromone robot FE2 transmits to sensing robots CS32, CS33 and CS34, amotion control signal for sensing robot CS including flutteringfrequency or direction of the fluttering robot, or a control signal forsensor control. Sensing robots CS30 and CS31 transmit to pheromone robotFE1, a signal for measuring power, for estimating distance betweensensing robot CS30 or CS31 to pheromone robot FE1.

From sensing robots CS32, CS33 and CS34 to pheromone robot FE2, a signalfor monitoring power for estimating distance between sensing robotsCS32, CS33 or CS34 to pheromone robot FE2 is transmitted.

Finally, sensing robot CS20 transmits to sensing robots CS30 and CS31, amotion control signal for the sensing robot including flutteringfrequency or direction of the robot, or a control signal for sensorcontrol. Sensing robot CS21 transmits to sensing robots CS32, CS33 andCS34, motion control signal for the sensing robot CS includingfluttering frequency or direction of the robot, or a control signal forsensor control.

Referring to FIG. 16, the flow of detection signals will be described.In this figure, solid lines in the lateral direction represent flow ofdetection signals, and vertical solid lines represent time delay.

First, from sensing robots CS30 and CS31 to sensing robot CS20, adetection signal representing presence/absence of an object or positioninformation is transmitted. From sensing robots CS32, CS33 and CS34,detection signal representing presence/absence of an object, positioninformation or the like is transmitted to sensing robot CS21.

Thereafter, from sensing robot CS20 to sensing robot CS11, a detectionsignal representing presence/absence of an object, position informationor the like is transmitted. From sensing robots CS21 and CSS22 tosensing robot CS12, a detection signal representing presence/absence ofan object, position information and the like is transmitted.

Finally, from sensing robots CS11 and CS12 to base station BS, adetection signal representing presence/absence of an object, positioninformation or the like is transmitted.

In this example, information is provided from the layer of sensing robotCS3k. When an object is detected by the layer of sensing robot CS2j orCS1i, information naturally starts from that layer, and transmittedupward to base station BS.

Communication between fluttering sensing robot CS and base station BS,between each of fluttering sensing robots CS and between base station BSand pheromone robot FE is performed in accordance with spread spectrumcommunication, which is a method of synchronous communication. Thespread spectrum communication system will be described with reference toFIG. 17 and Tables 1 to 4.

TABLE 1 BS CS1 (i-2) CS1 (i-1) CS1i A layer (synchronous) code 0 code 0code 0 code 0 B layer (up stream) — code 10 code 10 code 10 C layer(down stream) code 10 code 20 code 21 code 22

TABLE 2 CS (j-3) CS2 (j-2) CS2 (j-i) CS2j A layer (synchronous) code 0code 0 code 0 code 0 B layer (up stream) code 20 code 20 code 21 code 22C layer (down stream) code 30 code 31 code 32 code 33

TABLE 3 CS (k-3) CS3 (k-2) CS3 (k-1) CS3k A layer (synchronous) code 0code 0 code 0 code 0 B layer (up stream) code 30 code 30 code 30 code 31C layer (down stream) code 40 code 40 code 40 code 41

TABLE 4 FEn A layer (synchronous) code 0 B layer (up stream) code 10 Clayer (down stream) code 40

The group of robots of the group robot system in accordance with thepresent embodiment basically has three communication layers, includinglayer A for establishing synchronization, layer B for communication withrobots in the up stream, and layer C for communication with robots inthe down stream. In the layer A, base station 101, sensing robot CSgroups 102, 103, 104 and pheromone robot FE105 all have the same PN codeof 0. Here, code 0 is one of PN (Pseudorandom Noise) codes of 256 taps.

First, communication between base station BS101 and a sensing robotgroup 102 (CS11 to CS1i) in the down stream will be described. As thecommunication of layer A, base station BS101 communicates PN code 0 tosensing robot group 102 (CS11 to CS1i) by spread spectrum. Sensing robot102 (CS11 to CS1i) despreads, by multiplying the same PN code of 0, bythe received wave. When the PN code is despread for one period using amatched filter, for example, a point of synchronization where PN codesmatch can be found without fail.

Assume that the time point {circle around (1)} of FIG. 17 is a referencepoint of synchronization with base station BS101. The time ofsynchronization with sensing robot group 102 (CS11 to CS1i) is at thetime point {circle around (2)}. Namely, a peak of the matched filterappears at a time point delayed by the distance between base stationBS101 and sensing robot group 102 (CS11 to CS1i), where synchronizationis established.

Similarly, sensing robot group 102 (CS11 to CS1i) transmits, ascommunication of layer A, the PN code 0 to sensing robot group 103 (CS21to CS2j), by spread spectrum communication. The distance between basestation BS101 and sensing robot group 103 (CS21 to CS2j) is the distancebetween base station BS101 and sensing robot BS102 (CS11 to CS1i) plusthe distance between sensing robot 102 (CS11 to CS1i) and sensing robot103 (CS21 to CS2j), and therefore, the point of synchronization ofsensing robot 103 (CS21 to CS2j) with the base station appears is attime point {circle around (3)} of FIG. 17, further delayed from sensingrobot 102 (CS11 to CS1i).

Similarly, sensing robot group 103 (CS21 to CS2j) transmits as thecommunication of layer A, the PN code 0 to sensing robot group 104 (CS31to CS3k) by spread spectrum communication. The distance between basestation BS101 and sensing robot group 104 (CS31 to CS3k) is the distancebetween base station BS101 and sensing robot 103 (CS21 to CS2j) plus thedistance between sensing robot 103 (CS21 to CS2j) and sensing robot 104(CS31 to CS3k), and therefore, the point of synchronization of sensingrobot group 104 (CS31 to CS3k) with the base station appears at timepoint {circle around (4)} of FIG. 17, further delayed from sensing robot103 (CS21 to CS2j).

The distance between base station BS101 and pheromone robot FE105 forcontrolling movement, which will be described layer, is larger than thedistance between base station BS101 and sensing robot group CS104 (CS31to CS3k). Therefore, the point of synchronization of pheromone robot 105appears at time point {circle around (5)} of FIG. 17, further delayedfrom sensing robot group CS104 (CS31 to CS3k).

The point of synchronization of each robot described above is repeatedlyestablished intermittently, and the point of synchronization isconstantly updated. The point of synchronization of sensing robot 102(CS11 to CS1i) is represented by the time point {circle around (2)} ofFIG. 17.

For establishing communication with base station BS101 in the up stream,sensing robot 102 (CS11 to CS1i) performs despreading and demodulation,using PN code 10 of layer B. The point of synchronization of the PN codeof layer B is the time point {circle around (2)} of FIG. 17 that isestablished by the code 0 of layer A. Further, PN code 10 of layer B ofsensing robot 102 (CS11 to CS1i) is the same as the PN code 10 of layerC for establishing communication with the sensing robot of the downstream of base station BS101. Specifically, only the sensing robot group102 (CS11 to CS1i) that uses in layer B the same PN code 10 of the layerC of base station BS101 can communicate with base station BS.

In the example shown in Tables 1 to 4, the layer B of CS1 (i−2), CS1(i−1) and CS1i have the code 10, and therefore, these can communicatewith base station BS. However, sensing robot CS of which PN code oflayer B is not the code 10 cannot communicate with base station BS, asthe correlation peak with code 10 cannot be detected.

To establish communication with sensing robot 103 (CS21 to CS2j) of thedown stream, sensing robot 102 (CS11 to CS1i) performs despreading anddemodulation using PN codes 20, 21 and 22 of layer C. Point ofsynchronization of the PN code of layer C is the time point {circlearound (2)} of FIG. 17 established by code 0 of layer A. The PN codes20, 21 and 22 of layer C of sensing robot 102 (CS11 to CS1i) are thesame as PN codes 20, 21 and 22 of the layer B for establishingcommunication with sensing robot of the up stream of sensing robot 103(CS21 to CS2j).

Specifically, only that sensing robot 102 (CS11 to CS1i) that uses inthe layer C, the same PN code as the layer B of sensing robot 103 (CS21to CS2j) can communication with the sensing robot 103 (CS21 to CS2j) ofthe downstream. For example, CS1 (i−2) can communication with CS2 (j−3)and CS2 (j−2), CS1 (i−1) can communicate with CS2 (j−1), and CS1i cancommunicate with CS2j.

The point of synchronization of sensing robot 103 (CS21 to CS2j) is thetime point {circle around (3)} of FIG. 17. To establish communicationwith sensing robot 102 (CS11 to CS1i) of the up stream, sensing robot103 (CS21 to CS2j) performs despreading and demodulation using PN codes20, 21 and 22 of layer B. The point of synchronization of the PN code oflayer B is the time point {circle around (3)} of FIG. 17, established bythe code 0 of layer A. As the communication between sensing robot 103(CS21 to CS2j) and sensing robot 102 (CS11 to CS1i) has been alreadydescribed above, details will not be repeated here.

To establish communication with sensing robot 104 (CS31 to CS3k) of thedown stream, sensing robot 103 (CS21 to CS2j) performs despreading anddemodulation using PN codes 31, 32 and 33 of layer C. The point ofsynchronization of the PN code of layer C is the time point {circlearound (3)} of FIG. 17 established by code 0 of layer A. The PN codes30, 31, 32 and 33 of layer C of sensing robot 103 (CS21 to CS2j) are thesame as PN codes 30 and 31 of layer B for establishing communication ofsensing robot CS in the up stream of sensing robot 104 (CS31 to CS3k).

Specifically, only that sensing robot 103 (CS21 to CS2j) which uses inlayer C, the same PN code as the layer B of sensing robot 104 (CS31 toCS3k) can communicate with sensing robot 104 (CS31 to CS3k) of the downstream. For example, CS2 (j−3) can communicate with CS3 (k−3), CS3 (k−2)and CS3 (k−1), and CS2 (j−2) can communicate with CS3k.

The point of synchronization of sensing robot 104 (CS31 to CS3k) is thepoint {circle around (4)} of FIG. 17. To establish communication withsensing robot 103 (CS21 to CS2j) of the up stream, sensing robot 104(CS31 to CS3k) performs despreading and demodulation using PN codes 30and 31 of layer B. The point of synchronization of the PN code of layerB is the time point {circle around (4)} of FIG. 17 established by code 0of layer A. As the communication between sensing robot 104 (CS31 to CSk)and sensing robot 103 (CS21 to CS2j) has already been described above,details thereof will not be repeated here.

To establish communication with base station BS101 in the up stream,pheromone robot FE105 performs despreading and demodulation using PNcode 10 of the layer B. Point of synchronization of the PN code of layerB is the time point {circle around (5)} of FIG. 17 established by code 0of layer A. The PN code for synchronization of layer A is the same code0 as other sensing robots CS. The PN code 10 of layer B is the same asPN code 10 of layer C for establishing communication of base station BSwith sensing robot CS of the down stream. When the PN code of layer B isnot code 10, pheromone robot FE cannot communicate with base state BS,as correlation peak with code 10 of base station BS cannot be detected.

To establish communication with sensing robot 104 (CS31 to CSk) of thedown stream, pheromone robot FEn performs despreading and demodulation,using PN code 40 of layer C. The point of synchronization of the PN codeof layer C is the time point {circle around (5)} of FIG. 17 establishedby code 0 of layer A. The PN code 40 of layer C of pheromone robot FEnis the same as PN code 40 of layer C of sensing robot 104 (CS31 to CS3k)at the outermost position, for establishing communication with pheromonerobot FE.

Specifically, only that pheromone robot FEn that uses in layer C, thesame PN code as the C layer of sensing robot 104 (CS31 to CS3k) cancommunicate with sensing robot 104 (CS31 to CS3k) of the down stream. Inthe example shown in Tables 1 to 4, pheromone robot FEn can communicatewith sensing robots CS3 (k−3), CS3 (k−2) and CS3 (k−1) while it cannotcommunicate with CS3k, as the spread code is different.

As to the details of spread spectrum communication, see Yukiji Yamauchi,Spread Spectrum Communication, published by Tokyo Denki Daigaku ShuppanKyoku. In the spread spectrum communication of the present embodiment,by way of example, a spread spectrum communication apparatus describedin Japanese Patent Laying-Open No. 11-168407 is applied, which isproposed by the inventors of the present invention.

Next, a control system for controlling one fluttering sensing robot usedfor the group robot system described above (relation between the basestation and one fluttering sensing robot) will be discussed. Here, as anexample of the control of sensing robot CS by the base station BS,direct control of sensing robot CS by base station BS will be described.When base station BS controls a sensing robot CS of a lower layerthrough a sensing robot CS of a higher layer of the hierarchicalstructure, control signal related to fluttering operation and the likeis transmitted from sensing robot CS of a higher layer to a sensingrobot CS of a lower layer, and signals obtained by the sensor aretransmitted from sensing robot CS of a lower layer to a sensing robot CSof a higher layer, using control signals which will be discussed below.

(System Configuration)

First, system configuration of one fluttering sensing robot inaccordance with the present embodiment will be described with referenceto FIG. 18.

The control system of the fluttering sensing robot in accordance withthe present embodiment includes a work space 92 as an example of thesearch area C shown in FIG. 18, a robot 90 as an example of a flutteringsensing robot CS positioned in work space 92 and capable of flying andmoving within the space and capable of obtaining or changing physicalamount in the space, and a base station 91 as an example of the basestation BS that can exchange information with robot 90.

In the following, an object of searching of the invention will bedescribed, as an example, as a human.

Robot 90 as an example of the fluttering sensing robot CS of the presentembodiment obtains an amount of infrared ray, by an infrared sensormounted on itself, to detect a person 93 as the object of searching, anddirects a visible light to detected person 93 by using a light emittingdiode 8, so as to give some information to person 93.

(Detailed Description of Fluttering Sensing Robot of the PresentEmbodiment)

(Description of Robot 90)

(Main Configuration and Main Function)

First, main configuration of robot 90 as an example of the sensing robotin accordance with the present invention will be described withreference to FIG. 19.

As shown in FIG. 19, robot 90 has a support structure 1 as a mainstructure, on which various components are arranged. A right actuator 21and a left actuator 22 are fixed on an upper portion of supportstructure 1. A right wing 31 is attached to right actuator 21, and aleft wing 32 is attached to left actuator 22. An electrode 61 isarranged at a lower portion.

Actuators 21 and 22 allow wings 31 and 32 respectively attached theretoto rotate with three degrees of freedom, approximately about the fulcrumof the actuators. Rotation of each of the actuators 21 and 22 iscontrolled by a control circuit 4 mounted on support structure 1.Detailed structure of each actuator will be described later.

The center of gravity O of robot 90 in the state shown in FIG. 19 isvertically lower than the middle point A0 between centers of rotation ofleft and right actuators 21 and 22. Further, an acceleration sensor 51,an angular acceleration sensor 52 and a pyroelectric infrared sensor 53are mounted on support structure 1. Further, a communication apparatus 7is arranged on support structure 1. Communication apparatus 7transmits/receives information to and from the base station 91.

Control apparatus 4 detects the state of flight of robot 90 as thefluttering sensing robot, based on the information transmitted fromacceleration sensor 51 and angular acceleration sensor 52, and obtainsinformation of a heat source within the area 531 of detection by thepyroelectric infrared sensor, based on the information transmitted frompyroelectric infrared sensor 53. These pieces of information aretransmitted through communication apparatus 7 to base station 91.

Further, control apparatus 4 controls ON/OFF of light emitting diode 8arranged on support structure 1. Communication apparatus 7 receives aninstruction signal from the base station. In response to the instructionsignal, control apparatus 4 calculates operations of respectiveactuators 21, 22 and light emitting diode 8, and determines driving ofthese elements. The left and right actuators 21, 22, control apparatus4, sensors 51 to 53, communication apparatus 7 and light emitting diode8 are driven by a current supplied from a power source 6.

Power source 6 is a secondary battery, and is charged by power fedthrough electrode 61. Electrode 61 also serves as a positioning pin, andit can be placed in a fixed attitude, in a positioning hole of basestation 91.

Though electrode 61 consists of two pins, that is, positive and negativeelectrodes in FIG. 18, it may have three or more pins, including a pinfor detecting state of charge.

(Support Structure)

Support structure 1 will be described in greater detail with referenceto FIG. 19.

Desirably, the support structure 1 is sufficiently light weight, whileassuring mechanical strength. For the support structure 1 of robot 90 asthe fluttering sensing robot, polyethylene terephthalate (PET) mold toan approximately spherical shell is used. Support legs 11 are arrangedat the lower portion of support structure 1, so that the robot does notfall at the time of landing. Support legs 11 may be omitted whenstability at the time of landing is ensured, or stability at the time oflanding is not a problem functionally.

The material and the shape of support structure 1 are not limited tothose described with reference to FIG. 19, provided that flightperformance is not degraded. Particularly, the material of supportstructure 1 should be light weight and have high rigidity.

For example, a composite material provided by hybridization at molecularlevel of an organic substance such as chitosan observed in crabs orshrimps and inorganic substance such as silica gel may be used, torealize light weight and robust characteristics observed in exoskeletonsof crabs and shrimps as well as high susceptibility to shape-processing,directly utilizing optimal composition values of living organism. Suchmaterial is also environmentally friendly.

Further, calcium carbonate as the material of shells may be used inplace of chitosan mentioned above, to form the highly rigid supportstructure.

The arrangement and shape of the actuators and the wings are not limitedto those of the present embodiment.

Particularly, in the present embodiment, the center of gravity ispositioned lower than the mechanical point of application of the wing sothat the apparatus naturally assumes the attitude shown in FIG. 19,putting higher priority on stability of flight. However, the differencein fluid force between the left and right wings necessary for attitudecontrol becomes smaller when the position of the center of gravitymatches the position of the mechanical point of application, and hencethe attitude of robot 90 can be changed more easily. Therefore,dependent on application, such a design with higher priority onreadiness of attitude control may be possible.

(Mechanism of Flight)

(Wing and Its Operation)

Next, the wing and its operation will be described with reference toFIGS. 20 to 22.

For simplicity of description, a coordinate system is defined for FIG.19. First, approximately the center of support structure 1 is regardedas the origin. The direction of gravitational acceleration is regardedas the downward direction, and the opposite is regarded as the upwarddirection. The z axis is defined as extending from the origin to theupward direction. Next, the direction coupling the center of the shapeof right actuator 21 and the center of the shape of left actuator 22 isregarded as the left/right direction. The y axis is defined as extendingfrom the origin to the left wing. Further, the x axis is defined asextending in the direction of vector product, in the right hand systemof the y and z axes from the origin. The positive direction along thisaxis will be referred to as forward, and the opposite direction will bereferred to as backward.

In robot 90 as an example of the fluttering sensing robot shown in FIG.19, the center of gravity O is positioned on a line extending downwardalong the direction of gravitational acceleration from a midpoint A0between the point of application A1 of right actuator 21 of right wing31 and point of application A2 of left actuator 22 of left wing 32. Inthe present embodiment, a rotor 229 of the left actuator isapproximately spherical, and left wing 32 is arranged such that thecenter of the sphere of the rotor 229 is positioned on a line extendedfrom main shaft 321. The point of application A2 of left actuator 22 andthe fulcrum of rotating motion of main shaft 321 correspond to thespherical center. The same applies to right actuator 21.

In the following, it is assumed that the x, y and z axes described aboveconstitute a unique coordinate system of robot 90 fixed on supportstructure 1 in the state shown in FIG. 19.

Relative to the coordinate system fixed for robot 90, x′, y′ and z′ axesare defined as space coordinates fixed in the space and having anarbitrary point as the origin. Thus, the coordinates of the space inwhich the robot 90 moves can be represented by the coordinates of x′, y′and z′ axes, respectively, while the coordinates unique to the robot 90can be represented by the coordinates of x, y and z axes, respectively.

The wing structure will be described in the following. Left wing 32, forexample, is formed by spreading a film 323 over a support member havinga main shaft 321 and branches 322. Main shaft 321 is arranged at aposition closer to the front of left wing 32. Branches 322 are bentdownward near the tip end portions.

Left wing 32 has a convex cross sectional shape. Thus, high stiffness isobtained against the force exerted by the fluid especially in a downstroke. In order to reduce weight, main shaft 321 and branches 322 havehollow structure, and are formed of carbon graphite. Film 323 hasinitial stress in a direction of contraction in its plane, so as toenhance stiffness of the entire wing.

The diameter of main shaft 321 of the wing used for the experiment bythe inventors was 100 μm at the root supported by support structure 1and 50 μm at the tip end, and the main shaft 321 is tapered, madethinner from the root to the tip end portion. Film 323 is of polyimide,of which size is about 1 cm in the forward/backward direction, about 4cm in the left/right direction, and the thickness was about 2 μm.

In left wing 32 shown in FIG. 20, main shaft 321 is enlarged in itsthickness, for easier description. The right wing 31, not shown, isattached to the support structure to be mirror-symmetry with the leftwing 32, with the xz plane at the center.

The operation of the wing will be described with reference to the leftwing 32 as an example.

Left actuator 22 is capable of rotating left wing 32 with three degreesof freedom. Namely, the state of driving of left wing 32 can berepresented as the attitude of left wing 32. For the simplicity ofdescription, in the following, the attitude of left wing 32 will bedefined as follows, based on the state shown in FIG. 19.

First, referring to FIG. 21, using a plane parallel to the xy plane andincluding a fulcrum of rotational motion of the main shaft (mechanicalpoint of application A2) and axes (//x, //y) parallel to the x and yaxes, respectively, as a reference, an angle formed by a line connectingthe point A2 and the root of main shaft 321 of left wing 32 with thatplane is referred to as a stroke angle θ of fluttering. Further, using aplane parallel to the yz plane and including a fulcrum of the rotationalmotion of the main shaft (mechanical point of application A2) and axes(//y, //z) parallel to the y and z axes, respectively, as a reference,an angle formed by a line connecting the point A2 and the root of mainshaft 321 of the left wing 32 and that plane is referred to asdeclination α.

At this time, the stroke angle θ is considered positive when it is abovethe plane parallel to the xy plane, and negative when it is below thatplane. The declination α is considered positive when it is in front ofthe plane parallel to the yz plane and negative when it is behind.

Referring to FIG. 22, an angle formed by a tangential plane p1 of film323 at the root of main shaft 321 of left wing 32 with a plane p0passing through the point A2 and including the axis (//x) parallel tothe x axis and the main shaft 321 is referred to as torsion angle β.Here, the torsion angle β in the clockwise direction when viewed fromthe root to the tip end of main shaft 321 is considered positive.

(Actuator)

Actuators will be described with reference to FIGS. 23 to 27.

The actuator for operating the wing of robot 90 in accordance with thepresent embodiment is driven by progressive waves generated by apiezo-electric element (piezo element), as it has large torque, ensuresreciprocating operation and has a simple structure. Generally, anactuator referred to as an ultrasonic motor is used.

FIGS. 23 to 25 represent a commercially available ultrasonic motor 23.Referring to FIG. 23, a piezo-electric element 230 is adhered on a lowersurface of an aluminum disc 231, and projections 232 to 237 are providedat six positions, so as to form a regular hexagon, with the center ofthe disc being the center of gravity. Further, electrodes 238 dividedinto 12 along the circumferential direction are arranged on the lowersurface of piezo-electric element 230. FIG. 24 schematically shows thisstructure. Every other electrode is electrically short-circuited. Avoltage is applied, with the disc 231 being the reference, to eachelectrode.

Specifically, voltages of different phases are applied to thepiezo-electric element 230, as represented by hatched and non-hatchedportions of FIG. 25. By changing with time the voltage to be applied toeach electrode, a progressive wave is generated on disc 231, so that tipend portions of projections 232 to 237 perform elliptic motion,constituting a stator. The stator is capable of a rotor 239 arranged incontact with the stator such that the rotor is rotated along thecircumferential direction, by the elliptic motion of the tip ends ofprojections 232 to 237.

The ultrasonic motor 23 has the torque of 1.0 gf·cm, rotation speed withno-load of 800 rpm and maximum current consumption of 20 mA. Thediameter of disc 231 is 8 mm. Projections 232 to 237 are arranged at aninterval of 2 mm. The thickness of the disc 232 is 0.4 mm. The height ofprojections 232 to 237 is about 0.4 mm. Driving frequency ofpiezo-electric element 230 is 341 kHz.

In the present embodiment, an actuator utilizing this stator portion isused. Right actuator 31 has such a structure that has the sphericalrotor 219 pinched between a bearing 211 and a stator 210 similar to thestator described above, as shown in FIG. 27.

The portion of stator 210 which is in contact with rotor 219 isprocessed to conform to the surface of rotor 219. Rotor 219 is of aspherical shape having an outer diameter of 3.1 mm and an inner diameterof 2.9 mm, and right wing main shaft 311 is attached to the surfacethereof. When an operation is performed to convey rotor 219 clockwise tothat surface of stator 210 which has the projections thereof(hereinafter the rotation will be referred to as forward rotation, androtation in the opposite direction will be referred to as backwardrotation), the main shaft 311 of the right wing moves in the direction θof FIG. 27.

In order to drive rotor 219 with three degrees of freedom, an upperauxiliary stator 212, a lower auxiliary stator 213 and bearings 214 and215 are further arranged as shown in FIG. 26. The size of each auxiliarystator is about 0.7 times that of stator 210.

Though directions of driving respective stators are not necessarilyorthogonal, mutually independent rotations can be realized in theseelements. Therefore, by the combination of these motions, it is possibleto drive rotor 219 with three degrees of freedom.

For example, by causing forward rotation of rotor 219 by upper auxiliarystator 212 and generating forward rotation by lower auxiliary stator212, it is possible to rotate rotor 219 in the direction β. By causingbackward rotation of rotor 219 by upper auxiliary stator 212 and forwardrotation by lower auxiliary stator 212, it is possible to rotate rotor219 in the direction α.

In actual driving, combining two rotations of different centers ofrotation will lower efficiency, because of friction. Therefore, it isdesirable to adopt such a method of driving that the upper auxiliarystator 212 and the lower auxiliary stator 213 are operated alternatelyin a very short period, while the projection of the stator which is notin operation is prevented from contacting rotor 219. This can readily beattained without the necessity of adding any element, by applying avoltage to every electrode of the stator, in the direction ofcontraction of the piezo-electric element.

The frequency of piezo-electric element is at least 300 kHz, which issufficiently higher than the fluttering frequency which is, at most,about 100 Hz. Therefore, even when actuators are operated alternately,substantially smooth motion can be generated through the main shaft 311of the right wing. Therefore, an actuator with three degrees of freedomis provided, which has characteristics comparable to a conventionalultrasonic motor used for study by the inventors.

As the amplitude of the progressive wave generated by the stator is inthe order of submicrons, it is necessary that the rotor has thesphericity of this order. Processing accuracy of a paraboloidal mirrorused in civil optical products is about several tens nm, and processingaccuracy of optical components used for optical interferometer is aboutseveral nm. Therefore, it is possible to form such a rotor by existingprocessing method.

It should be understood that this is only an example of an actuatorrealizing motion with three degrees of freedom of the wing implementedby an ultrasonic motor. Arrangement, size, material and the method ofdriving various components are not limited to those described above,provided that physical functions such as torque required for flutteringflight can be realized.

Further, it should be understood that the wing driving mechanism and thetype of actuator used therefor are not limited to those described in thepresent embodiment. For example, fluttering flight using a combinationof exoskeleton structure and a linear actuator such as proposed inJapanese Patent Laying-Open No. 5-169567 may be possible, as wingoperation equivalent to that provided by the actuator of the presentembodiment is realized.

Though electric power is used as driving energy, an internal combustionengine may be used. An actuator utilizing physiologicaloxidation-reduction reaction for converting chemical energy to kineticenergy, as can be seen in the muscle of insects, may be used. Forexample, muscle obtained from insects may be used as a linear actuator,or artificial muscle of composite material by combining, at a molecularlevel, amino acid of protein of the muscle of an insect with aninorganic substance may be used as a linear actuator.

It is also possible to provide an actuator with high energy efficiencysuch as the internal combustion engine mentioned above for basic drivingpower, and an actuator driving with electric power may be used forcontrolling the same or as an assistant.

(Method of Flight)

The method of flight will be described next, with reference to FIGS. 28to 34.

Here, the force received by the wing from the fluid will be referred toas fluid force. For simplicity of description, it is assumed that airflow occurs only by the fluttering, that is, the apparatus is in aperfectly calm state.

For simplicity of description, it is also assumed that external forceacting on robot 90 is only the fluid force received by the wing from thefluid and the gravity.

For the robot 90 to fly constantly, it is necessary that the followingrelation is satisfied in average of one fluttering operation.

(Sum of Vertically Upward Fluid Forces Acting on the Wing)>(GravityActing on Robot 90).

Here, a method by which the fluid force in a down stroke is made largethan the fluid force in an up stroke will be described, which methodcorresponds to a simplified manner of fluttering of an insect. Forsimplicity of description, the behavior of the fluid or the force of thefluid on wing will be described with reference to main componentsthereof. The magnitude of the buoyancy force obtained by the flutteringand the gravity acting on robot 90 will be described later.

On the wing, fluid force in the direction opposite to the direction ofmotion of the wing acts. Therefore, in a down stroke of the wing, fluidforce acts upward on the wing, and in an up stroke, fluid force actsdownward on the wing. Therefore, an upward fluid force can be obtainedby time average in one fluttering operation (down stroke and up stroke),when fluid force for the down stroke is made larger and the fluid forcefor the up stroke is made smaller.

For this purpose, the down stroke should be such that the volume of aspace in which the wing moves is maximized, so that almost maximum fluidforce acts on the wing. This corresponds to down stroke of the wingapproximately vertical to the tangential plane of the wing.

For the up stroke, the wing should be moved upward such that the volumeof the space in which the wing moves is minimized, so that the fluidforce acting on the wing is almost minimized. This corresponds to upstroke of the wing approximately along the curve of wing cross section.

Such operation of the wing will be described with reference to a crosssection vertical to the main shaft 321 of the wing. FIG. 28 shows a downstroke made to maximize the volume of the space in which the wing movesand FIG. 29 shows an up stroke made to minimize the volume of the spacein which the wing moves.

In FIGS. 28 and 29, the position of the wing before movement isrepresented by a dotted line, and the position of the wing aftermovement is represented by the solid line. Further, the direction ofmovement of the wing is represented by a chain dotted arrow. Further,the direction of the fluid force acting on the wing is represented bysolid arrows. As can be seen in the figures, the fluid force acts on thewing in the direction opposite to the direction of movement of the wing.

In this manner, the attitude of the wing is changed relative to thedirection of movement of the wing such that the volume of the space inwhich the wing moves in the up stroke is made larger than the volume ofthe space in which the wing moves in the down stroke, whereby the upwardfluid force acting on the wing can be made larger than the gravityacting on the robot 90 as the sensing robot, in time average of onefluttering operation.

In the present embodiment, torsion angle β can be controlled, and theabove described wing motion is realized by changing with time thetorsion angle.

More specifically, the following steps S1 to S4 are repeated. First, instep S1, the wing is moved downward as shown in FIG. 30 (stroke angleθ=+θ₀→−θ₀). In step S2, the wing rotation 1 operation (torsion angle βof the wing=β₀→β₁) is performed as shown in FIG. 31. In step S3, thewing is moved upward as shown in FIG. 32 (stroke angle θ=−θ₀→+θ₀,torsion angle β=β₁→β₂ (a motion along the curve of the wing crosssection so as to maintain the fluid force minimum)). In step S4, wingrotation 2 operation (torsion angle β of the wing=β₂→β₀) is performed asshown in FIG. 33.

When the fluid forces acting on the wing in steps S1 and S3 aretime-averaged upward fluid force, because of the difference in space inwhich the wing moves, as described above. Relation of magnitude betweenthe vertical component of the upward fluid force and gravity will bedescribed later.

Naturally, it is desired that time-average of the fluid forces acting onthe wing in steps S2 and S4 results in upward fluid force.

In the fluttering apparatus, the center of rotation of the wing (theportion of main shaft 321) is positioned near a front edge of the wing,as shown in FIGS. 30 to 33. More specifically, the length from mainshaft 321 to the rear edge of the wing is longer than the length frommain shaft 321 to the front edge of the wing. Therefore, as shown inFIGS. 31 to 33, in the rotating operation of the wing, in addition tothe flow of the fluid generated along the direction of rotation of thewing, a flow of the fluid is generated along the direction from the mainshaft 321 to the rear edge of the wing.

As a reaction of such flows of the fluid, forces opposite in directionto these flows act on the wing as a result, therefore in step S2 shownin FIG. 31, substantially upward fluid force is applied to the wing, andin step S4 shown in FIG. 33, mainly downward fluid force is applied tothe wing.

In step S3 shown in FIG. 32, an up stroke is made with the torsion angleβ changed from β₁ to β₂ along the curve of the wing cross section. Theangle of rotation of the wing in step S2 shown in FIG. 31 is larger thanthe angle of rotation of the wing in step S4 shown in FIG. 33.Therefore, in steps S2 and S4 also, the fluid force acting upward on thewing becomes stronger than the fluid force acting downward, and by timeaverage, an upward fluid force acts on the wing.

In FIGS. 30 to 33, the attitude of the wing before movement inrespective steps 1 to S4 is represented by the dotted line and theattitude after movement is represented by the solid line. The directionof movement of the wing in respective steps S1 to S4 is represented bythe chain dotted arrow. The flow of fluid mainly generated in steps S1to S4 is represented by solid arrows.

FIG. 34 is a graph representing the values of stroke angle θ and torsionangle β as functions of time. In FIG. 34, it is noted that the ratios ofthe ordinates for the stroke angle θ and torsion angle β are different.

In the experiment performed by the inventors, θ₀ is, for example, 60°.The value β₀ is, for example, 0°, β₁ is −120° and β₂ is −70°.

In the description, steps S1 to S4 are described as independentoperations, for simplicity of description. An operation, however, isalso possible in which the torsion angle of the wing is enlarged whilethe wing is moved downward in step S1.

Further, the example described above comes from primary approximation,and the method of fluttering that actually enables rising is not limitedthereto.

Though description has been made with respect to the left wing, the sameapplies to the right wing, by defining the stroke angle θ, declination αand torsion angle β for the left hand system, which is inmirror-symmetry with respect to the xz plane. In the following, theupward fluid force acting on the wing will be referred to as buoyancyforce, and a forward fluid force acting on the wing will be referred toas propulsion.

(Method of Control)

The method of control enabling arbitrary motion of robot 90 will bedescribed next. Here, the stroke angle θ, declination α and torsionangle β based on the right hand system will be used for the left wingand the stroke angle θ, declination α and torsion angle β based on theleft hand system in mirror symmetry with respect to the xz plane areused for the right wing, to represent the attitude of the wings.

(Control Flow)

The flying movement by fluttering is realized by the fluid force exertedon the wing. Therefore, what is directly controlled by the wing motionis acceleration and angular acceleration applied to the robot 90.

First, the process through which an output Se is obtained from an inputS is as shown in FIG. 59, where S represents difference between thetarget state of flight and the present state of flight, T(S) is afunction representing conversion from the state of flight toacceleration and angular acceleration, s represents acceleration,angular acceleration Fα(s) represents a function of a control algorithmincluding sensor response of acceleration sensor 51 and angularacceleration sensor 53, sα represents actuator control amount, Gw (sα)is a function representing response of actuator and the wing, swrepresents wing motion, G_(fs) (sw) is a function representingacceleration or angular acceleration s_(e) exerted on the robot 90 bythe wing motion, and Se represents change in the state of flightattained by the series of processes.

Actually, by the inertial force of the wing and the fluid, influences Rwand R_(fs) that depend on time history of the wing motion and the fluidmotion so far are added to Gw and G_(fs).

(Division of Operation)

There is naturally a method of accurately calculating all functionsother than Fα to calculate control algorithm Fα which realizes S=Se. Forthis method, time history of the fluid flow around the flutteringapparatus and the wing motion is necessary, which means that aformidable amount of data and high speed of arithmetic operation arenecessary. The behavior resulting from the link between the fluid andthe structure is so complicated that in most cases, the response wouldbe chaotic, and hence such a method is impractical.

Therefore, a method in which basic operation patterns are prepared inadvance, the target state of flight is divided and realized bytime-sequentially combining the basic operation patterns is desired, asit is simple.

A motion of an object includes three translational degrees of freedom inx, y and z directions, and three rotational degrees of freedom in θ_(x),θ_(y) and θ_(z) directions, that is, 6 degrees of freedom. Namely,freedom in forward/backward directions, left/right directions andupward/downward directions as well as rotations in these directions.

Among these, the movement in left/right direction can be realized bycombining rotation in the θ_(z) direction and movement in theforward/backward direction. Therefore, here, the method of realizingtranslational movement in the forward/backward direction, that is, alongthe x axis, translational operation in the upward/downward direction,that is, along the z direction and rotational operations about the x, yand z axes will be described.

(Operation)

(1) Operation in the Upward/Downward Direction (Along the z Axis)

As the wing moves, the force exerted by the fluid on the wing depends onthe speed of movement of the wing, and therefore, in order to increase(decrease) the upward fluid force acting on the wing, possible optionsinclude

A: to increase (decrease) amplitude of stroke angle θ, and

B: to increase (decrease) fluttering frequency.

By such operation, the robot 90 may move upward (downward). Here, it isnoted that the fluid force includes a negative value.

According to such approaches, the fluid force itself from the fluid tothe wing increases. When there is any force exerted from a directionother than the upward/downward direction from the wing to the mechanicalfulcrum of the wing as the fluid force is received by the wing from adirection other than the upward/downward direction, as the apparatusmoves upward, the force acting on the fulcrum also increases in thatdirection. For example, when the apparatus is making a substantiallyuniform, forward linear motion and the fluttering frequency isincreased, the fluttering apparatus moves upward with the velocityincreased. In this manner, such a secondary motion occurs depending onthe manner of fluttering at that time point. In the following, controlfrom the hovering state will be described, unless noticed otherwise.

Further, the buoyancy force changes when the volume of the space inwhich the wing moves is changed by changing the torsion angle β of thewing. For example, by setting an angle β such that the volume of thespace in which the wing moves in an up stroke is larger or the volume ofthe space in which the wing moves in a down stroke is smaller, the timeaverage of the upward fluid force acting on the wing becomes smaller.

Actually, the wing is not a rigid body and it deforms. Therefore, thevolume of the space in which the wing moves differ even when the angle βis the same. According to the primary principle, the angle β which isvertical to the direction of movement of the wing provides the largestvolume of the space in which the wing moves. Further, the angle β whichis parallel to the direction of movement of the wing provides thesmallest volume of the space in which the wing moves.

Here, secondary, the fluid force also acts in the direction vertical tothe fluttering. If this action is of such a level that causes anyproblem in control, it becomes necessary to add wing motion that cancelssuch an action. It is realized, in the simplest manner, by changing thedeclination α.

It is also possible to perform the operation along the z axis bychanging the rotational angular speed of the wing in the above describedstep S2 or S4. For example, when the rotational angular speed (−dβ/dt)of the wing is increased in step S2, downward flow rate of the fluidgenerated by the rotation increases, and by the reaction thereof, theupward fluid force acting on the wing increases.

Here, the torque of which axis of rotation is the main shaft of thewing, which acts on the robot 90, changes as a secondary result.Therefore, the change of the rotational angular speed should desirablybe performed within such a range in that the change of the torque doesnot affect control.

Further, here the force in the forward/backward direction acting on therobot 90 also changes as a secondary result. Therefore, if the changeaffects controlled flight, control of the force in the forward/backwarddirection should desirably be performed simultaneously, which will bediscussed in item (2) below.

(2) Operation in the Forward/Backward Direction (Along the x Axis)

In the above described method of fluttering, the fluid force in the xdirection acts on the wing mainly in steps S2 and S4. Therefore, by suchan operation of the wing, the apparatus rises while moving forward.

When the declination α is increased in a down stroke and the wing ismoved forward, a backward fluid force will act on the wing. Therefore,when the backward fluid force acting on the wing in step S1 is madelarger than the forward fluid force mainly in the steps S2 and S4, theapparatus moves backward, and when the backward fluid force is madesmaller, the apparatus moves forward, by controlling declination α instep S1, that is, in the down stroke. When these two forces aresubstantially balanced, the apparatus can stand still in theforward/backward direction.

Especially, when the robot 90 stands still in the forward/backwarddirection, the left and right wings perform substantially symmetricalmotions and the gravity is balanced with the buoyancy force of thefluttering apparatus, hovering is possible.

As the vertical component of the fluid force acting on the wing changesas a secondary result of the change in declination α, it becomesnecessary to add wing motion that cancels this component, if thecomponent is of such a level that affects control. This is mainlyperformed, in a simple manner, by the operation in the upward/downwarddirection described in item (1) above.

Further, when the angular velocity of rotational operation of the wingis increased in steps S2 and S4 described above, forward fluid forceincreases, and when it is decreased, the fluid force decreases. Thus,operation in the forward/backward direction can be changed.

Further, it is possible to utilize the component in the x direction ofthe secondary fluid force associated with the change in torsion angle βof the wing described in item (1). More specifically, when β>0 in a downstroke, there is a forward force and when β<0, there is a backwardforce, on the apparatus.

Though the relation between each of β, α and θ in an up stroke islimited to some extent, the above described fluid force control is alsopossible in step S3.

(3) Rotational Operation with z Axis Being the Axis of Rotation

By performing the control in the forward/backward direction described initem (2) separately for the left wing and the right wing to be differentfrom each other, a torque can be applied to the fluttering apparatus.

More specifically, when the forward fluid force on the right wing ismade higher than that of the left wing, the robot 90 turns to the leftwith respect to the positive direction along the x axis, and when it ismade lower, the apparatus turns to the right.

(4) Rotational Operation with x Axis Being the Axis of Rotation

Similar to (3), when the upward fluid force of the right wing isincreased to be larger than that of the left wing, the right side islifted and when it is made smaller, the left side is lifted. Thus,rotational operation about the x axis as the axis of rotation ispossible.

(5) Rotational Operation with y Axis Being an Axis of Rotation

By changing the angular velocity of torsion angle β of the wingdescribed in (2), the torque about the y axis acting on the robot 90 canbe changed. Thus, rotational operation about the y axis as the axis ofrotation is possible. For example, when the rotational angular velocityof torsion angle β in step S1 is increased, the nose of the flutteringapparatus moves downward, and when it is decreased, the nose movesupward.

(6) Hovering

FIG. 35 is a graph representing the values of the stroke angle θ,declination α and torsion angle β when the fluttering apparatus ishovering, as functions of time. In FIG. 35, the ratio of the angles aredifferent from that of the coordinate.

In the experiment performed by the inventors, by way of example, θ₀ is60°, β₀ is −10°, α₁ is 30°, β₁ is −100° and β₂ is −60°.

FIG. 60 represents motions of the left wing in respective steps andacceleration and angular acceleration generated by the motions at themechanical fulcrum A2 of the left wing. It is noted, however, thatrotational operation about the x and z axes as axes of rotationdiscussed in (3) and (4) above are not shown. These operations areattained by asymmetrical motions of the left and right wings, as alreadydescribed.

(Manner of Determining Control Method)

The present status of flight is found by using values that are providedby appropriately changing the values obtained by acceleration sensor 51or angular acceleration sensor 52 mounted on the robot 90. For example,the velocity can be calculated by applying an initial value of velocityto a value obtained by time-integration of acceleration. The positioncan be calculated by applying an initial value of position to the valueobtained by time-integration of velocity. Further, it is also possibleto use a method which includes time history of flying status, to findthe status of flight.

Control apparatus 4 determines operation of the robot 90 based on thecurrent status of flight obtained from acceleration sensor 51 andangular acceleration sensor 52 and the target status of flight.Conventional control method is applicable to this control, except thatthe present control is in three dimensions.

The operation of the robot 90 is converted by control apparatus 4 todriving of the actuators. This conversion may be realized at high speedwhen table reference or complementation thereof is used. For example,basic operations and combinations of actuator drivings realizing theoperations are prepared in advance, as shown in FIG. 61. In FIG. 61, theleftmost column represents target operation. Fluttering patterns A and Brepresent the pattern of fluttering for forward movement and forhovering, respectively, which are, more specifically, time-discrete timehistories of α, β and θ represented in the graphs of FIGS. 34 and 35.Control apparatus 4 calculates the drive or the complemented drive fromthe table, based on the operation of robot 90.

Here, a method in which the operation of the fluttering apparatus iscalculated and converted to actuator drive is used for convenience ofdescription. It is also possible, however, to select driving of actuatordirectly from the status of flight.

For static control, for example, a method is possible in which of theactuator drives described above or complementation thereof may directlybe calculated.

It is needless to say that physical amount representing the status offlight of the fluttering apparatus is not limited to the position,velocity, acceleration and the like mentioned above.

Further, the method of determining actuator drive is not limited tothose described above.

(Weight that can be Lifted)

Next, the condition that enables lift of the configuration of robot 90in accordance with the present embodiment will be described withreference to FIG. 36 in the experimental environment of the inventors, aprogressive wave actuator is used as the actuator. When the progressiveactuator is used, stator 210 is comparable to ultrasonic motor 23.Therefore, the torque with respect to the motion in θ direction is 1.0gf·cm. Therefore, the inventors calculated the fluid force when therobot flutters with this torque, through simulation.

The wing is a rectangular having longer side of 4 cm and shorter side of1 cm with the longer side in the direction away from the actuator, anddeformation of the wing is neglected. As the mass of wing of a dragonfly having the width of 8 mm and the length of 33 mm was about 2 mg, themass of the wing was made 3 mg, based on the values.

The ultrasonic motor 23 drives the rotor by accumulation of smallelliptical motions at the tip end portion of the projections. Therefore,rise and fall of the actual driving torque is in the periodic order ofelliptical motion, that is, in the order of 10⁵ Hertz. However, becauseof limitation from calculation stability, it was set to ±250 gf·c/sec.Namely, the torque increases by 1 gf·cm per every 0.004 sec.

One shorter side of the wing is fixed, leaving on the rotational degreeof freedom with this side being the access of rotation, the torque isapplied to the rotational degree of freedom, and reaction on the axis ofrotation was calculated, with the result being shown in FIG. 36. Here,as defined above, declination α=0°, and secondary angle β=0°.

At time 0, the wing is horizontal (stroke angle θ=0°). The torque valueis substantially linearly increased to 1 gf·cm from time 0 to 0.004 sec.From the time point 0.004 sec to 0.01 sec, the torque value is kept at 1gf·cm. From 0.01 sec to 0.018 sec, the torque value is substantiallylinearly changed from 1 gf·cm to −1 gf·cm. From time point 0.018 sec to0.03 sec, the torque value is kept at −1 gf·cm. From time 0.03 sec to0.038 sec, the torque value is substantially linearly changed from −1gf·cm to 1 gf·cm.

The time-average of the fulcrum reaction during a down stroke, that is,from time 0.014 sec to 0.034 sec where the torque is negative, was about0.29 gf.

As the simulation provides the result of fluttering operation with onedegree of freedom, the action of the fluid force in an up stroke isunknown. The resistance of the fluid, however, decreases as comparedwith the cross section, and therefore, considering the fact that thedownward fulcrum reaction acting in the up stroke is small and that upstroke with the same torque as for the down stroke is possible, the timenecessary for the up stroke is considerably shorter than the timenecessary for the down stroke.

The time of action of the force is relatively short in the up stroke andbuoyancy force can also be obtained by wing rotation or the like inaddition to that down stroke. Therefore, it is considered possible tolift an object having the mass of about 0.29 g, by using an actuatorhaving the torque of 1 gf·cm. More specifically, when the mass of theentire fluttering sensing robot of the present embodiment is made atmost 0.58 g, the fluttering robot can be lifted. The weight of thefluttering robot will be considered in the following.

First, stator 210 has the mass of 0.054 g, as it is comparable to a dischaving the specific gravity of 2.7, thickness of 0.4 mm and the radiusof 4 mm, as the electrode and the piezo-electric elements are thin.

The weight of the auxiliary stator is 0.019 g, as the diameter of thestator is 0.7 times the diameter of stator 210.

Three bearings are each a doughnut shaped ball bearing having the outerdiameter of 4.2 mm, inner diameter of 3.8 mm and the thickness of 0.4mm. The material of the bearing is titanium having the specific gravityof 4.8. As the bearing has an opening of about 30%, the mass of thebearing is about 0.013 g. The rotor is formed of aluminum and has wallcenter radius of 3 mm and the thickness of 0.2 mm. Thus, it is about0.06 μg. The mass of the actuator as the total sum of these is 0.192 g.Further, the wing is 0.003 g. as mentioned above. As there are right andleft two such structures, the total is 0.390 g.

The support structure 1 employed by the inventors shown in FIG. 19 is asphere having the diameter of 1 cm, specific gravity of 0.9 and thethickness of 0.1 mm. Therefore, the mass is about 0.028 g. Controlapparatus 4, communication apparatus 7, acceleration sensor 51, angularacceleration sensor 52 and pyroelectric infrared sensor 53 employed bythe inventors are each of a semiconductor bare chip of 5 mm×4 mm, eachhaving the weight of about 0.008 g. Thus, total mass of these is 0.04 g.

The power source 6 employed by the inventors has the weight of 0.13 g.

Therefore, the total weight of all the components is 0.579 g. As thebuoyancy force obtained by one pair of wings is 0.58 gf, the structurecan be lifted.

(Communication Apparatus)

The communication apparatus 7 will be described in the following.

Communication apparatus 7 has the function of transmission, andtransmits measurements of various sensors. Thus, base station 91 canobtain information from robot 90.

The information obtained by base station 91 includes physical amounts ofrobot 90 or environment therearound. Specifically, examples of theformer include acceleration information of robot 90 obtained from theacceleration sensor and angular acceleration information of robot 92obtained by angular acceleration sensor 52, and an example of the latteris infrared amount information obtained by pyroeletric infrared sensor53.

Further, communication apparatus 7 has a function of reception, andreceives control signals. Consequently, base station 91 can controlrobot 90.

Control signals transmitted from base station 91 include control signalsrelated to the state of flight of robot 90, and control signals forchanging physical amounts of the environment around robot 90.

Specifically, examples of the former include signals for designatingacceleration and angular acceleration to be applied to robot 90, and anexample of the latter includes a signal designating intensity of lightemitting diode 8.

The present embodiment will be described assuming that information asmentioned above is transmitted/received.

It is needless to say that information to be transmitted/received is notlimited thereto. For example, an acknowledge signal for confirmingwhether the control signal issued from based station 91 is correctlyreceived by robot 90 or not may also be transmitted/received.

(Control Apparatus)

Control apparatus 4 will be described in the following, with referenceto FIGS. 19 and 38.

Referring to FIG. 19, control apparatus 4 includes an operatingapparatus 41 and a memory 42. Operating apparatus 41 has a function oftransmitting information obtained by various sensors of robot 90 throughcommunication apparatus 7. Operating apparatus 41 also has a function ofcontrolling operation of each component, based on a control signalobtained through communication apparatus 7. Memory 42 has a function ofholding these transmitted/received data.

In the present embodiment, specifically, operating apparatus 41calculates acceleration and angular acceleration of robot 90 based onthe information from acceleration sensor 51 and angular accelerationsensor 52, and transmits the information to base station 91, throughcommunication apparatus 7. Further, from base station 91, information ofacceleration and information of angular acceleration to be applied torobot 90 at present are transmitted. This pieces of information arereceived through communication apparatus 7, and operating apparatus 41has a function of determining operation parameter of each actuator,based on the received acceleration and angular acceleration.

More specifically, operating apparatus 41 has time-sequential values ofα, β and θ corresponding to representative combinations of accelerationand angular acceleration to be applied to robot 90, in the form of atable, and these values or interpolated values thereof are used as theparameters for operation of each actuator. The time-sequential values ofα, β and θ represent discrete values, of the values shown in the graphof FIG. 34 which shows a case of hovering, where acceleration andangular acceleration are both 0.

It is understood that α, β and θ are examples of the control parameters,and for simplicity of description, it is assumed that the actuator isdriven by designating these parameters. It is efficient to useparameters converted to driving voltage or control voltage to eachactuators that implements this in more linear manner. As these are notparticularly different from the existing method of actuator control, α,β and θ are listed simply as representative parameters, and parametersare not limited to this.

As a specific example of another function, operating apparatus 41 has afunction of transmitting information provided from pyroelectric infraredsensor 53 through communication apparatus 7.

Accordingly, it becomes possible for base station 91 to obtain infraredinformation of the infrared information detecting area 531 by thepyroelectric infrared sensor 53 mounted on robot 90.

Further, operating apparatus 41 has a function of receiving a lightemission control signal of light emitting diode 8 transmitted from basestation 91 through communication apparatus 7, and controlling currentflowing through light emitting diode 8 in accordance with the controlsignal. Thus, it becomes possible for base station 91 to control lightemission of light emitting diode 8. Functions of control apparatus 5 arenot limited to those described here.

As flight control is linked to time, it may be possible to storeoperation time-history of the wing in memory 42 of control apparatus 4,and means may be provided to correct control signals from base station91 in accordance with the time-history information.

When flight and movement of robot 90 are given priority, it may bepossible that there is generated a data that cannot be transmitted fromthe communication band. Further, disruption of communication is alsopossible. In view of these, it is effective to mount a memory 42,provided that increase in weight does not hinder flight movement.

On the other hand, except for the registers of operating apparatus 41,these are not explicitly essential to the function of robot 90.

(Driving Energy Source)

The driving energy source, that is, power source 6 will be described.

The left and right actuators 21, 22, control apparatus 4, sensors 51 to53 are driven by power supplied from power source 6.

Power source 6 uses lithium ion polymer has an electrolyte, andtherefore, it may be sealed within support structure 1. Thus, extrastructure for preventing leakage of liquid becomes unnecessary, andsufficient energy density can be increased.

A commercially available lithium ion polymer secondary battery generallyhas mass energy density of 150 Wh/kg, and current consumption by theactuator in the present embodiment is at most 40 mA. Therefore, when theweight of electrolyte of power source 6 is about 0.1 g, flight for about7.5 min is possible in the present embodiment. Further, the maximumcurrent consumption of actuators of the present embodiment is, as atotal of left and right actuators, 40 mA.

Further, the power supply voltage is 3V. As the weight of electrolyte is0.1 g, the power source 6 must have weight power density of 0.12 W/g,that is, 1200 W/kg. A commercially available lithium ion polymersecondary battery has weight power density of about 600 W/kg, which isfor a product having the weight of log or heavier, used in aninformation equipment such as a portable telephone.

Generally, the ratio of electrode area with respect to the mass ofelectrolyte is in inverse proportion to the size of the power source.The power source 6 of the present embodiment has the ratio of electrodearea larger by ten times or more than the secondary battery used in aninformation equipment mentioned above. Therefore, the power source canattain the mass power density of about ten times higher, and hence, theoutput power density mentioned above can sufficiently be attained.

It is also possible to externally supply the energy for driving theactuators. For example, temperature difference, electromagnetic wave orthe like may be used as medium supplying power energy from the outside,and a thermionic element or a coil may be used as the mechanism forinverting each of these two driving energy.

It is also possible to mount energy sources of different types. When anenergy source other than electric power is used, basically, it iscontrolled by using an electric signal from control apparatus 4.

(Sensors (Physical Amount Input Portion))

The sensors will be described in the following.

Acceleration sensor 51 detects translational acceleration with threedegrees of freedom of support structure 1, angular acceleration sensor52 detects rotational acceleration with three degrees of freedom ofsupport structure 1, and pyroelectric infrared sensor 53 detects theamount of infrared rays in pyroelectric infrared sensor detecting area531. Results of detection by sensors 51 to 53 are transmitted to controlapparatus 4.

The acceleration sensor used by the inventors has the band of 40 Hz. Thehigher the band, acceleration sensor 51 or angular acceleration sensor52 is capable of performing control more precise in time. The change inthe state of flight of robot 90 is considered as a result of one or morefluttering, and therefore, a commercially available sensor having theband of about several ten Hz may be used practically.

In the present embodiment, position and attitude of robot 90 aredetected by the acceleration sensor and the angular acceleration sensor.Sensors are not limited to those and any mean may be used provided thatposition and attitude of robot 90 can be measured. For example, at leasttwo angular sensors capable of measuring accelerations in three axialdirections orthogonal to each other may be arranged at differentpositions of support structure 1, and the attitude of robot 90 may becalculated based on the acceleration information provided from eachacceleration sensor.

Further, a method may be possible in which ground wave is explicitlyincorporated in work space 92, which wave is detected by robot 90 tocalculate position and attitude. For example, a magnetic fielddistribution may be provided in work space 92, and a magnetic sensor maydetect the magnetic field distribution, to calculate position andattitude of robot 90. Further, a method may also be possible that uses aGPS sensor.

Further, a method is also possible in which position and attitude ofrobot 90 are directly detected outside robot 90, for example, by basestation 91. For example, base station 91 may have a camera, and theposition of robot 90 may be calculated by image processing. In thatcase, naturally, acceleration sensor 51 or the like is not essential inrobot 90.

Though sensors including acceleration sensor 51 and angular accelerationsensor 52 are expressed as components separate from control apparatus 4,in view of achieving light weight, these may be formed on one siliconsubstrate integral with control apparatus 4, by micro machiningtechnique.

The sensors of the present embodiment are minimum requirements forachieving the object of application, that is, security, and types,numbers and configurations of the sensors are not limited to thosedescribed above.

For example, wings of robot 90 are driven under control without anyfeedback. A wing angle sensor may be provided at the root of the wing,and the wing can be driven more accurately by feeding back angularinformation obtained from the sensor.

On the other hand, when air flow in the area of flight is known and itis possible to reach target position simply through a predeterminedmanner of flight, it becomes unnecessary to detect the state of flightof robot 90. Therefore, in that case, acceleration sensor 51 and angularacceleration sensor 52 are not essential. For detecting a human, amethod employed in a conventional robot can be utilized, by usingpyroelectric infrared sensor 53.

The human 93 as an object of searching described as an example of thepresent embodiment is also an obstacle of movement for robot 90. Whenpyroelectric infrared sensor detecting area 531 is arranged below robot90, it becomes possible for robot 90 to detect human 93 while flying,and hence human 93 does not become an obstacle but can be detected.

Though a pyroelectric infrared sensor which is inexpensive and widelyused at present has been described as an example of a sensor fordetecting a human, possible sensor is not limited thereto, and anysensor may be used provided that the function of detecting a human isattained.

(Light Emitting Diode (Physical Amount Output Portion))

Light emitting diode 8 will be described in the following.

Light emitting diode 8 has a visible light illumination area thatgenerally covers the pyroelectric infrared sensor detection area 531 ofpyroelectric infrared sensor 53. The operation of light emitting diode 8is controlled by control apparatus 4.

The above described configuration, when control apparatus 4 determinesthat a source of infrared radiation detected in pyroelectric infraredsensor detection area 531 is a human 93, it is possible to perform anoperation of directing visible light thereto. Though light emittingdiode 8 is described as an example of the physical amount output portionin the present embodiment, it is not limiting.

In order not to degrade mobility of robot 90 in determining thecomponents described above, the component should desirably be lightweight, while functions of the components are not degraded.

(Description of Base Station)

(Main Configuration and Main Function)

Main configuration and function of base station 91 will be describedwith reference to FIG. 37. As the main object of the base station is toobtain information from robot 90 and to control robot 90 based thereon,FIG. 37 simply shows a specific example, and appearance, shape andpresence/absence of accessories are not limited to those described here,provided that the object is attained.

Referring to FIG. 37, base station 91 includes an operating apparatus911, a memory 912 and a communication apparatus 917. Communicationapparatus 917 has a function of receiving a signal transmitted fromrobot 90. Further, it has a function of transmitting a signal to robot90.

Base station 91 has a function of determining activity of robot 90,based on various pieces of information including map data of work space92 stored in memory 912 and acceleration information of robot 90received from robot 90 through communication apparatus 917. Further, ithas a function of transmitting the activity through communicationapparatus 917 to robot 90.

By the above described reception function, activity determining functionand transmission function, base station 91 can control robot 90 throughcommunication function, based on the information of robot 90 itself orinformation of environment around the robot.

An upper surface of base station 91 is used as a take off/landing baseof robot 90. Specifically, a charger 913 is provided on the uppersurface of base station 91, and electrodes 61 of robot 90 are coupled tocharging holes 914, so that the robot is electrically connected to powersource 6, to be ready for charging. In order to save power, charger 913is controlled by operating apparatus 911, and operates even while robot90 is coupled with base station 91 to charge, in the present embodiment.

The charging holes 914 also serve as positioning holes. Further, anelectromagnet 915 is provided on base station 91, to attract robot 90 asneeded. More specifically, relative position of robot 90 with respect tobase station 91 before take off is fixed by the operation ofelectromagnet 915, and relative speed is 0.

(Operation Instruction)

In the present embodiment, base station 91 includes operating apparatus911, memory 912 and communication apparatus 917, and it has a functionof transmitting to robot 90 through communication apparatus 917,acceleration and angular acceleration to be applied to robot 90, basedon various pieces of information including acceleration information ofrobot 90 received from robot 90, in accordance with the map data of workspace 92 stored in memory 912 and predetermined path of robot 90 in workspace 92 to attain a pre-set object. For example, attitude of robot 90can be calculated by integrating twice the information of angularacceleration of robot 90.

By twice integrating this and acceleration information in absolutecoordinate system obtained by rotation transformation of accelerationinformation of robot 90 with attitude of modes, the position of robot 90can be calculated. As for the constants of these integration operations,velocity and angular velocity before take off are both 0, and as therobot is fixed in charging holes 914 of base station 91, position andattitude are always known. Thus, operating apparatus 911 can calculateposition and attitude of robot 90 and provide control instruction torobot 90.

Through the above described functions, it is possible for base station91 to control robot 90 such that robot 90 patrols work space 92. Thesefunctions can naturally be correlated with each other. For example, fromthe acceleration information and angular acceleration information ofrobot 90, it is possible to calculate the position of infrared detectionarea 531 for pyroelectric infrared sensor 53 in work space 92.

By mapping the position and the amount of infrared ray, position, shapeand operation of infrared radiation source can be calculated, and thediode may be operated to direct light to the vicinity of center ofgravity of the infrared radiation source. Wide variation is possible andoptimum design is selected for each application. Therefore, the examplesdescribed above are not limiting.

(Method of Patrol)

The method of patrol by robot 90 can be implemented by adding degree offreedom in the height direction, to the conventional method of patrolused for a robot moving over the floor by wheels and the like.

For example, a method of patrolling a three-dimensional space can berealized by adding degree of freedom in the height direction to thepatrol on a two-dimensional plane, by once performing patrol at aprescribed height and thereafter, height of robot 90 is changed andpatrol is again performed at a different height.

Dependent on the detection distance of pyroelectric infrared sensor 53,it may substantially be possible to detect a human from the whole workspace 92 when the robot patrols at a certain height. In that case,patrol is possible simply by the algorithm for patrol on atwo-dimensional plane proposed conventionally.

As to the route of patrol, a certain path may be prepared in advance inmemory 912, or, alternatively, operating apparatus 911 may calculate,using information from map data in memory 912 as a reference. Forexample, a method may be possible in which importance in patrol ofportions in work space 92 may be designated, and frequency of patrol maybe set higher in accordance with the importance. The path may be changedduring patrol. For example, when a human is detected, the robot may bekept hovering at the position of detection.

The foregoing describes a simple example of the method of patrol of workspace 92 by robot 92, and not limiting. The mass of base station 91 hasno influence on the flight of robot 90, and therefore, highlycomplicated path or method of patrol can readily be determined.

(Assistance in Take off and Landing)

At the time of start or end of fluttering, that is, at the time of takeoff and landing of robot 90, air flow caused by fluttering abruptlyincreases or decreases and is unstable. Therefore, it is difficult tocontrol position and attitude of robot 90. In the present embodiment,electromagnet 915 provided on base station 91 attracts robot 90 in thestage before take off. At the time of take off, until air flow caused byfluttering becomes stable, electromagnet 915 is operated, and attractionby electromagnet 915 may be stopped when air flow becomes stable. Bysuch a method, stable take off becomes possible.

At the time of landing, robot 90 is moved such that electrodes 61 areroughly positioned above charging holes 914, electromagnet 915 isactivated in this state, and robot 90 is attracted to base station 91.When fluttering is stopped thereafter, position and attitude at the timeof landing with unstable air flow, can be stabilized. In order tofacilitate positioning, either one or both of electrodes 61 and chargingholes 914 should be tapered.

If weight permits, robot 90 may have electromagnet 915. When suchconfiguration is taken, it becomes possible to robot 90 to performstable take off/landing to and from every substance formed offerromagnetic or soft magnetic material, in addition to base station 91.In order to enable take off with smaller acceleration, it is possible toprovide an inner force sensor in electromagnet 915, and attraction forceof electromagnet 915 may be controlled in accordance with the forcesensed by the inner force sensor.

The foregoing merely represents an example of the method to preventunstable flight of robot 90 resulting from unstable air flow at the timeof take off and landing. Any means may be used provided that robot 90 istemporarily held at the time of take off and landing. For example,suction by air in place of electromagnet 915 may be possible. Further,take off and landing along a guide mechanism such as a rail is alsopossible.

(System Operation)

Robot 90 patrols work space 92 in accordance with an instruction frombase station 91 to detect a human. A specific example will be describedwith reference to FIGS. 38 and 39. The following description is by wayof example only and not intended to limit the scope of protection.

(Stationary State)

Before the start of operation of robot 90, robot 90 is fixed on basestation 91 with the electrodes 61 connected to charging holes 914. Powersource 6 is charged as needed. It is assumed that operating apparatus911 and memory 912 are already in operation in base station 91. Further,it is assumed that the route of patrol by robot 90 has already beencalculated by operating apparatus 911. It is also assumed that lightemitting operation of the diode of robot 90 upon detection of a humanhas already being calculated by operating apparatus 911. It is desirablethat the route of patrol and diode light emitting operation are storedin memory 912.

(Take Off, Elevation)

Electromagnet 915 of base station 91 operates, and robot 90 is attractedto base station 91. In this state, robot 90 starts fluttering operationto rise in the vertical direction. Acceleration sensor 51, angularacceleration sensor 52, control apparatus 4 and communication apparatus7 of robot 90 have started operation by the time attraction byelectromagnet 915 is stopped, at the latest. At this time, communicationapparatus 917 of base station 91 also has started its operation, and itis necessary that operating apparatus 911 is in a state ready to detectthe state of flight of robot 90.

When air flow caused by fluttering becomes stable, electromagnet 915stops attraction of robot 90. When attraction of electromagnet 915becomes weaker than the point of balance where attraction force ofelectromagnet 915 is equal to the lift force of robot 90, robot 90starts rising.

By the time robot 90 starts rising, operating apparatus 911 of basestation 91 must have started operation to find position and attitude ofrobot 90, at the latest.

Robot 90 rises while transmitting acceleration information and angularacceleration information to base station 91. Based on these pieces ofinformation and position and attitude of robot 90 calculated inaccordance with the target route, base station 91 calculatesacceleration to be applied at present to robot 90, and provides aninstruction to robot 90. When robot 90 reaches the position designatedin advance, robot 90 starts patrol at this height, in accordance withthe instruction from base station 91.

(Patrol)

Before the start of patrol, pyroelectric infrared sensor 53 isactivated. Infrared information thereof is transmitted by communication,to operating apparatus 911. Patrol is performed such that base station91 provides instruction of movement to robot 90, monitors infraredinformation, and determines presence/absence of heat source, that is,the source of infrared emission. In order to avoid obstacles, the robotgenerally patrols at the height of about 2 m, that is, higher than theaverage height of an intruder. Robot 90 patrols work area 92 thoroughly,for example, by reciprocating in the work area shifted little by littleby the width of about 60% of the width of infrared information detectionarea 531.

(Landing)

After the end of patrol, the pyroelectric infrared sensor 53 of robot 90stops its operation. At the end of patrol, base station 91 controlsrobot 90 such that robot 90 lowers while maintaining its position andattitude so that electrodes 61 of robot 90 are positioned verticallyabove the charging holes 914 of base station 91. When it is determinedthat robot 90 is at a position where attraction by electromagnet 915 ispossible, electromagnet 915 is activated, and robot 90 is fixed on basestation 91.

After robot 90 is fixed on base station 91, operations of accelerationsensor 51 and angular acceleration sensor 52 of robot 90 are stopped.After the robot 90 is fixed on base station 91, base station 91instructs robot 90 to stop fluttering. Communication apparatus 7,control apparatus 4 and the like may be stopped thereafter.

(Flow Chart)

FIG. 38 shows flow of various pieces of information in the presentembodiment. FIG. 39 is a flow chart of the operation described above.These are examples only, and operation of robot 90 satisfying theapplication as a sensing robot searching for an object of the presentembodiment is not limited thereto. The operation may differ in differentapplications.

(Communication)

Method of communication in the present embodiment will be described withreference to FIGS. 40 to 42.

Here, data to be communicated will be discussed mainly. Though there arevarious methods as to the detailed manner of communication includingcommunication protocol and hand shake timing, any method may be used,provided that data described herein can be exchanged.

(Stationary State, Take Off)

First, communication operation in the stationary state to take off willbe described with reference to FIG. 40.

First, operating apparatus 911 and communication apparatus 917 of basestation 91, as well as control apparatus 4 and communication apparatus 7of robot 90 are activated, so as to establish connection between robot90 and base station 91. Then, electromagnet 915 of base station 91 isactivated to attract robot 90, so as to prevent fall of robot 90 causedby unstable air flow at the time of take off.

Acceleration sensor 51 and angular acceleration sensor 52 of robot 90must be active before the robot starts rising, that is, beforeacceleration or angular acceleration changes from 0, in order toaccurately grasp position and attitude of robot 90. Therefore, sensingmust be started before the start of fluttering.

Base station 91 provides an instruction of fluttering to rise, to robot90. In the present embodiment, instruction of acceleration and angularacceleration is provided to robot 90, so that the robot flutters to risevertically upward.

In robot 90, a time-sequential pattern of α, β and θ is selected toenable vertically upward lift, from a control table prepared in advance,and in order to start fluttering in accordance with the pattern, leftand right actuators are driven.

Base station 91 waits until air flow caused by the fluttering of therobot is stabilized using, for example, a timer to detect lapse of aprescribed time period, and thereafter, lowers attraction force ofelectromagnet 915.

During this period, robot 90 transmits acceleration information andangular acceleration information of itself to base station 91 bycommunication. When attraction force of electromagnet 915 becomes lowerthan the lift force, robot starts rising. This is detected as the speedof robot is no longer 0. When lift is completed, lift completion signalis transmitted from base station 91 to robot 90, and patrol mode starts.

(Patrol)

Communication operation during patrol will be described with referenceto FIG. 41.

Before the start of patrol mode, the infrared sensor of robot 90 isactivated (not shown).

Thereafter, robot 90 obtains information from various sensors. Theobtained sensor information is transmitted by communication, to basestation.

Of the received sensor information from robot 90, base station 91 mapsinfrared information, and calculates infrared radiation distribution inwork space 92. From acceleration information and angular accelerationinformation, position and attitude of robot 90 are calculated. It isassumed that the process for calculating position and attitude and theprocess for infrared mapping are continuously performed during thepatrol.

Based on the result of infrared mapping, when there is recognized aninfrared radiation source that does not exist in the map data of memory912, the source may be regarded as a human and alarming operation usingthe light emitting diode may be possible. Otherwise, patrol iscontinued. Such an operation to be taken next is determined by basestation 91, and acceleration and angular acceleration for robot 90 aretransmitted as instruction information, to robot 90.

Based on the acceleration instruction and the angular accelerationinstruction among the received instruction information, robot 90calculates driving state of left and right actuators referring to acontrol table prepared in advance, and controls the actuators. Whenthere is an instruction of alarming operation, robot drives LEDaccordingly. In the alarming operation also, the manner of communicationis the same as in the patrol operation, except for the driving of LED.

When base station 91 determines that robot 90 has completed patrol, thebase station transmits a patrol end signal to robot 90, and landing modestarts.

(Landing)

Communication at the time of landing will be described with reference toFIG. 42.

After the end of patrol, robot 90 stops operation of pyroelectricinfrared sensor 53.

Base station 91 guides robot 90 directly above the landing position,specifically, an area where robot 90 can be attracted to the initialposition by means of electromagnet 915. Similar to the control at thetime of patrol, the robot is guided by using the position and attitudeof robot 90 calculated based on the acceleration information and angularacceleration information received from robot 90. Namely, it is performedthrough the same manner of communication as in the patrol operation.

When robot 90 reaches directly above the landing position, electromagnet915 is activated, so to as attract robot 90 to the base station. When itis unnecessary to operate continuously thereafter, base station 91instructs end of operation to robot 90. Thus, fluttering operation,communication operation and sensing of robot 90 are terminated.

The manner of communication is not limited to the one described above,provided that it is a single system and that the base station providesinstruction of action to robot 90 based on the sensor information fromrobot 90.

Though sensors are described as operating continuously in the presentembodiment, a method is also possible in which sensor operatesintermittently, in accordance with an instruction from base station 91,such that the sensor operates only when a sensor information requestsignal is received from base station 91.

(Function Sharing)

Function sharing related to information processing by control apparatus4 of robot 90 and base station 91 will be described in the following.

Robot 90 and base station 91 can exchange information throughcommunication path, and therefore, functions of each of these can beshared in various ways. For example, as in the embodiment above, robot90 may have all the functions of base station 91 and base station 91 maybe eliminated, that is, a so-called stand alone type robot is alsopossible. However, when excessive mass is mounted on robot 90, flightbecomes difficult.

Quick movement is possible when robot 90 is light weight, and efficiencyof system operation can be increased. Therefore, generally, it isdesired that most of information processing is performed by base station91 and robot 90 is designed to be light weight. Particularly, map dataof work space 92 becomes larger dependent on the size of the work spaceand the number of obstacles.

Therefore, it is desired that a memory 912 that does not lead toincreased weight to be mounted on robot 90, is prepared. Whenspecification of the position of infrared radiation source mentionedabove is performed by operating apparatus 911 of base station 91, itbecomes possible to use a simple device as the control apparatus 4 ofrobot 90. Therefore, weight of the robot can be reduced.

In addition to the discussion above, in considering sharing of functionsrelated to information processing by control apparatus 4 of robot 90 andbase station 91, it must be kept in mind that improve in communicationspeed leads to increased weight.

For example, consider communication using radio waves. When the speed ofcommunication increases, it becomes necessary to use radio wave of highfrequency having higher energy, as a carrier. This leads to larger powerconsumption. As a result, the weight of power source 6 increases. Inaddition, signal quality must be improved by using a compensationcircuit, for example. This means increase in number of components, andhence the weight increases for the communication function. It isnecessary to design actual sharing of functions, generally consideringsuch trade off.

Consider, for example, that details of fluttering, that is, wing anglesα, β and θ are also designated by base station 91. Generally, frequencyof fluttering flight is several ten Hz or higher, and therefore, controlfrequency band of α, β and θ is in the order of kHz. Here, assume thateach data of α, β and θ consist of 8 bits, communication rate of 8(bit)×1 (kHz)×3×2 (number of actuators)=48 (kbps) for a singlecommunication path is necessary, in order to control each angle with 1kHz. This is the rate for transmission only, and actually, a band forreception is also necessary. Further, communication overhead and datafrom sensors including pyroelectric infrared sensor 53 are added, andtherefore, a communication method having the communication rate of about100 kbps becomes necessary.

Basic operations such as forward movement, rearward movement and turn tothe left or right of robot 90 can be attained by preparing prescribedpatterns of fluttering, corresponding to each of such operations.Therefore, it may be possible that basic operations and flutteringpatterns to attain the same are contained in robot 90, base station 91calculates basic operation suitable for the scheduled path and gives aninstruction to robot 90, and robot 90 selects fluttering patterncontained therein, in accordance with designated basic operation,whereby robot 90 can fly through a desired path.

This manner of control, in which robot 90 controls high frequency rangerepresented by the control of manner of fluttering itself and basestation 91 controls low frequency band represented by path control isdesirable in view of reduction of amount of calculation by the controlapparatus and reduction in traffics of communication path. The basicoperations and the fluttering patterns to attain the same shoulddesirably be prepared as a table in control apparatus 4, in view ofprocessing speed and reduction in amount of calculation by controlapparatus 4.

It is naturally expected that capability of operation of the operatingapparatus represented by control apparatus 4 and communication rate willsignificantly be improved in the future. Therefore, the manner ofinformation processing by robot 90 and base station 91 are simpleexamples of the basic idea at present, and specific sharing of functionsis not limited to the manner described above.

(Height Control)

According to the present embodiment, the robot can move easily to adifferent floor, by height control. Specifically, when heightinformation is included in the map data, simply by adding control inheight direction to the conventional method of controlling robot movingon a floor, patrol path can be changed in height. Specifically, when therobot moves flying with its height changed in accordance with analgorithm in accordance with the map data of stairs, for example, bykeeping constant a vertical distance from the vertically lower surfaceof the stairs, the robot can easily move upward/downward over thestairs.

Use of stairs to a different floor described above is merely an exampleof a method to move to a different floor, and not limiting. For example,a ventilating hole or a blow-by may be utilized.

(Plurality of Patrols)

Though an example of single patrol has been described, the manner ofpatrol is not limiting. For example, the patrol operation described inthe present embodiment may be repeated.

Further, patrol may be performed newly, by the above described methodsof patrol. Though an operation in which the robot returns to the basestation after the end of patrol has been described in the embodimentabove, it is merely an example and not limiting. For example, aplurality of base stations may be arranged in work space 92, and therobot may patrol between the base stations.

(Energy Replenishing Mechanism)

It is naturally understood that the method or manner of charging powersource 6 described above is simply an example of energy replenishmentgenerally used for attaining both light weight and continuous operation.Any power source 6 and charging mechanism therefor may be used providedthat the function of a power source can be satisfied.

For example, a coil may be formed on the wing by sputtering a metal,radio wave may be externally applied and the radio wave is converted topower and rectified by the coil, to charge power source 6.

Alternatively, a charging station may be provided simply for the purposeof charging, in addition to base station 91, and the robot may becharged there.

When energy other than electric power is to be used, appropriate methodof energy replenishment becomes necessary. The shapes of electrode 61and charging hole 914 are not limited to those described in theembodiment above. Further, it is not essential that the function ofpositioning is also attained by these as described in the embodimentabove.

(Communication)

In the present embodiment, it is assumed that base station 91 alwaysobtains information from robot 90 and controls robot 90 accordingly. Itis not always necessary that base station 91 controls robot 90, forexample, when autonomous operation is possible by robot 90.

Further, by temporarily holding information in memory 42, frequency ofcommunication between base station 91 and robot 90 may be decreased.This approach is effective when it is necessary to reduce traffic overcommunication path, for example, when there are a plurality of robots ora plurality of base stations, as will be described later.

It is desirable that connection between robot 90 and base station 91 isdesigned considering possibility of disruption. By incorporating inadvance a method of operation when communication path is disrupted inrobot 90, undesirable influence of communication disruption can beminimized, when connection is resumed.

As an example, robot 90 may have a function of maintaining constantstate of flight, that is, hovering, when communication path isdisrupted. In that case, possibility of collision against an obstaclecan be reduced than when the robot continues to move without hovering.

By buffering some operation model ahead in memory 42, robot 90 cancontinue flying even when communication path is disrupted. Conversely,when information detected by sensors is buffered in memory 42 and basestation 91 utilizes the buffered information after the resumed ofcommunication path is resumed, base station can obtain information ofthe sensors while the communication path has been disrupted.

Further, utilizing such buffering approach, it becomes possible toattain the function of the group robot system with weaker radio wave inan environment containing a number of obstacles and hindrance of radiowave is a likely. Therefore, power consumption can be reduced and weightof power source 6 can be reduced. Thus, mobility of robot 90 isimproved.

(Change in Environment)

In the present embodiment, for simplicity of description, it is assumedthat environment in work space 92 is not changed. In actual use,however, environment changes. The main cause of change in environmentincludes generation of air flow and change in obstacles. When there aresuch changes in environment, it is necessary to prepare means forcorrecting accordingly.

Fluttering flight receives influence of air flow similar to a generalairplane. Therefore, method used for designing path of a generalairplane can directly be applied for its correction.

As to the change in environment, the method employed in a conventionalremote control robot system can directly be applied. For example, meansfor detecting obstacles such as an optical sensor may be provided onrobot 90, data base of obstacle detection may be transmitted to basestation, and base station 91 may update map data based on theinformation.

(System Configuration (Number of Robots and Base Stations))

For simplicity of description, it has been assumed that there is onebase station in the embodiment above. It is naturally possible tocontrol robot 90 by a plurality of base stations. As an example, whenwork space 92 is wider than the range of communication between basestation 91 and robot 90, a plurality of base stations may be provided tocover work space 92, so as to spatially share control of robot 90.

In the present embodiment, the function of controlling robot 90,functions of assisting take off/landing and function of energyreplenishment, that is, function of charging are integrated in basestation 91. Integration of these functions in the base station is notessential. For example, when the distance of continuous flight, that is,the distance the robot can continuously fly without supplementingdriving energy from the outside is shorter as compared with thecommunication range, an energy replenishment station may exist in thecommunication range covered by one base station.

On the other hand, there may be two or more robots 90. Sufficiency ofsearching in work space 92 can be improved when a plurality of robotsare used. For example, assume that a human is to be searched as in thepresent embodiment. When it takes a time period T1 (sec) for robot 90Ato search the work space 92 once, frequency of searching of a certainposition in work space 92 would be 2/T1 (times) when searching by robot90B is started after T1/2 (sec) from the start of searching by robot90A. Namely, searching with double frequency is possible. Accordingly,possibility of finding a human can be improved. Alternatively, robotsthat operate as a group modeling migration of fish may be used.

Naturally, when all the functions of base station 91 can be incorporatedin robot 90 and the weight of the robot is light enough to enableflight, robot 90 may be used by itself, as a stand alone type robot.Alternatively, it is possible that base station 91 is responsible formass information processing and robot 90 has actuator only, as thecontrol portion.

In the group robot system of the present embodiment, the robot obtainslift force and moves away from the ground. Therefore, it is possible forthe robot to move in a room, for example, where there are many objectssuch as furniture and the positions of the objects move with time,avoiding such obstacles, to perform a prescribed operations such asgrasping the states of each room. Further, the robot can move freelyoutdoors, not hindered by obstacles at a disaster site, or geometry in ageneral field, for example, to easily perform an operation ofinformation collection. Further, it can be introduced to existing workspace at a low cost in a simple manner.

According to the group robot system in accordance with the presentinvention, including the robot having information from the robot throughcommunication capable of controlling robot, information processing bythe robot can be realized by components having no influence on lifting.Therefore, the amount of information to be processed can be increasedwithout degrading mobility of the robot.

Another embodiment of the robot will be described in the following.

(Another Embodiment)

A group robot system using a fluttering sensing robot in accordance withanother embodiment will be described. The group robot system of thepresent embodiment is approximately the same as the embodiment above,except for the structure of the fluttering sensing robot. Specifically,the fluttering sensing robot in accordance with the present invention isused in the group robot system of the form of the embodiment above, andtheir relation with the base station and communication control is alsothe same. The same applies to a situation where the fluttering sensingrobot is used as a pheromone robot. Though fluttering flight of thefluttering sensing robot only will be described in the presentembodiment, sensors similar to those described above are provided assensors for detecting the object on the fluttering sensing robot, andthe same communication mechanism as above is provided as a communicationmechanism that enables communication with other fluttering sensingrobot, pheromone robot or base station, utilizing spread spectrumcommunication through hierarchical structure.

FIG. 43 shows the fluttering sensing robot having two wing shafts as thewing portion, in which the left side shows a front view of thefluttering sensing robot and the right side shows a left side view,viewed from the front face of the fluttering sensing robot.

Though only the left wing viewed from the front face of the flutteringapparatus is shown in FIG. 43, actually, a right wing is also formed inline symmetry with respect to the central axis of a main body 105. Forsimplicity of description, it is assumed that an axis (main body axis801) along the direction of extension of main body 105 is in ahorizontal plane, and that a central axis 802 passing through the centerof gravity is kept in the vertical direction.

As can be seen from FIG. 43, on main body 105 of the flutteringapparatus, a wing (left wing) is formed, which has a front wing shaft103 and a rear wing shaft 104 and a wing film 106 provided bridgingacross the front and rear wing shafts 103 and 104.

Further, a rotary actuator 101 for driving front wing shaft 103 and arotary actuator 102 for driving rear wing shaft 104 are mounted on mainbody 105. Such an arrangement of actuators 101 and 102 as well as theshape of the wing including front wing shaft 103, rear wing shaft 104and wing film 106 are not limited to those described herein, providedthat the flight function is assured.

Further, in the fluttering sensing robot, when the cross sectional shapeof the wing is adapted to protrude vertically upward, a reaction as wellas lift are generated for the flight in the horizontal direction,resulting in larger buoyancy force.

The position of center of gravity of the fluttering sensing robot is setto be lower than the point of application of the force received by thewing from ambient fluid to the actuator, to enhance stability of thefluttering apparatus. When quick change of the attitude of thefluttering apparatus is of higher priority, it is desirable that thecenter of gravity and the point of application are substantially thesame. In that case, difference of the force exerted by the fluid on theleft and right wings necessary for attitude control becomes smaller, andhence change in attitude of the fluttering apparatus becomes easier.

Two rotary actuators 101 and 102 have a common axis of rotation 800. Theaxis of rotation 800 forms a prescribed angle (90°−θ) from the axis ofthe main body. Front (rear) wing shaft 103, 104 performs a reciprocatingoperation in a plane that orthogonally crosses the axis of rotation 800,with the actuator 101, 102 being a fulcrum. The angle formed by theplane orthogonally crossing the axis of rotation 800 and the axis 801 ofthe main body is the angle of elevation θ.

In order to ensure both mechanical strength and light weight, main body105 should desirably be formed by polyethylene terephthalate (PET)molded to a cylindrical shape. The material and the shape, however, arenot limiting.

An ultrasonic progressive wave actuator using a piezo-electric elementis desirable as the actuators 101 and 102, as it has large activationtorque, enables reciprocating operation in a simple manner and has asimple structure. Such an actuator is classified into two types, thatis, rotary actuator and linear actuator. In the example shown in FIG.43, rotary actuators are used.

A method of directly driving the wing by an ultrasonic element usingprogressive wave will be mainly discussed in the following. Themechanism for driving the wing and the type of the actuator usedtherefor, however, are not limited to those described with respect tothe present embodiment.

As the rotary actuator, a rotary actuator 401 shown in FIG. 53, forexample, may be used, other than the rotary actuators 101 and 102 shownin FIG. 43.

In the fluttering sensing robot shown in FIG. 53, a wing 403 is attachedto a rotary actuator 401 mounted on main body 404. Wing 403 performs areciprocating operation about the rotation axis 402 of rotary actuator401.

As a mechanism for driving the wing, a mechanism having an exoskeletonstructure and a linear actuator combined, as described in JapanesePatent Laying-Open No. 5-1695675, may be applied to provide such afluttering apparatus as shown in FIG. 54 or 55, for example.

In the fluttering sensing robot shown in FIG. 54, a front wing shaft ora rear wing shaft 503 is connected to one end of a linear actuator 501.Motion of linear actuator 501 is transmitted to the front or rear wingshaft 503 through a hinge 502 attached to main body 504, so thatfluttering motion occurs. The fluttering motion is conceived from thefluttering motion of a dragonfly with the wing of which is directlydriven by the muscle.

In the fluttering sensing robot shown in FIG. 55, the main body isdivided into an upper main body 603 and a lower main body 604. Motion ofa linear actuator fixed on lower main body 604 is transmitted to uppermain body 603. The motion of upper main body 603 is transmitted to thefront or rear wing shaft 603 through a hinge 602, and the flutteringmotion occurs. This fluttering operation is conceived from thefluttering operation of a bee, not the dragonfly.

In the fluttering sensing robot shown in FIG. 55, the left and rightwing shafts 603 are simultaneously driven by one actuator 601, andtherefore, separate driving of left and right wing shafts is notpossible. Therefore, delicate flight control is impossible. However, asthe number of actuators can be reduced, weight and power consumption canbe reduced.

In the fluttering sensing robot shown in FIG. 43, front wing shaft 103and rear wing shaft 104 are respectively connected to rotary actuators101 and 102. A wing film 106 is provided between the front and rear wingshafts 103 and 104. The wing film 106 has initial stress in a directionof contraction in its plane, which serves to enhance stiffness of theentire wing.

In order to reduce weight, front and rear wing shafts 103 and 104 areformed to have a hollow structure, from carbon graphite. Thus, the frontand rear wing shafts 103 and 104 have elasticity, and front and rearwing shafts 103 and 104 are deformable by the tension of wing film 106.

FIG. 56 shows an overall structure of the fluttering apparatus of thepresent invention. The wing on the left side along the direction ofprogress (upward on the sheet) is not shown. On a main body 700, anultrasonic sensor 701, an infrared sensor 702, an acceleration sensor703 and an angular acceleration sensor 704 are arranged. Results ofdetection by these sensors are transmitted to a fluttering controlportion 705.

Fluttering control portion 705 processes information such as distancebetween the fluttering apparatus and an obstacle or a person near theapparatus, from the results detected by the ultrasonic sensor 701 orinfrared sensor 702. Further, information such as the state of flight,target position or attitude of the fluttering apparatus is processedfrom the results detected by acceleration sensor 703 or angularacceleration sensor 704, and driving control of left and right actuators706 and a center of gravity control portion 707 is determined.

Though ultrasonic sensor 701 and infrared sensor 702 are used as meansfor detecting an obstacle existing around the fluttering sensing robotand acceleration sensor 703 and angular acceleration sensor 704 are usedas means for detecting position and attitude of the fluttering sensingrobot, the sensors are not limited to these, and any sensor that canmeasure environmental conditions, position and attitude of the presentfluttering sensing robot may be used.

For example, the attitude of the fluttering apparatus can be calculatedfrom acceleration information obtained by arranging two accelerationsensors capable of measuring acceleration in three axial directionsorthogonally crossing with each other, arranged at different positionsof main body 700. Further, it is possible to calculate position andattitude of the fluttering apparatus by providing a magnetic fielddistribution in the space in which the fluttering apparatus moves, andby detecting the magnetic field distribution by a magnetic sensor.

In FIG. 56, sensors represented by acceleration sensor 703 and angularacceleration sensor 704 are shown as components separate from flutteringcontrol portion 705. In order to reduce weight, the sensors may beformed integrally with and on the same substrate as fluttering controlportion 705 by micromachining technique, for example.

Though wing drive is open-loop controlled in the present flutteringapparatus, closed-loop control is also possible by providing an anglesensor of the wing at a root of the wing and using angle informationobtained from the angle sensor.

When flow of the fluid in the space where the apparatus flies is knownand flight is possible in accordance with a predetermined method offluttering, the sensors listed above are not essential.

Fluttering control portion 705 is connected to a memory portion 708, andexisting data necessary for fluttering control may be read from memoryportion 708. Further, information obtained by sensors 701 to 704 may befed to memory portion 708 and to rewrite information in memory portion708 as needed, whereby the fluttering sensing robot may have learningfunction.

When the information obtained by sensors 701 to 704 is to be simplystored in memory portion 708, sensors 701 to 704 may be directlyconnected to memory portion 703, not through fluttering control portion705. Alternatively, fluttering control portion 705 may be connected tocommunication control portion 709, for data input to/output fromcommunication control portion 709. Communication control portion 709transmits/receives data to/from an external apparatus (other flutteringapparatus, a base station or the like) through an antenna portion 710.

Such a communication function enables speedy transfer of data obtainedby the fluttering sensing robot and stored in memory portion 708 to anexternal apparatus. Further, it is possible to receive from an externalapparatus information that cannot be obtained by the fluttering sensingrobot and to store such information in memory portion 708, so that suchinformation can be used for fluttering control. Without storing a largeamount of map information fully in the fluttering sensing robot, it ispossible to obtain map information of a desired area as needed from abase station.

Though antenna portion 710 is shown as a bar protruding from an end ofmain body 700 in the example shown in FIG. 56, it may have any shape orarrangement provided that an antenna function is attained. For example,a loop shaped antenna may be formed on the wing, utilizing front wingshaft 712 or rear wing shaft 713. Alternatively, the antenna may becontained in main body 700, or the antenna and communication controlportion 709 may be integrated.

Ultrasonic sensor 701, infrared sensor 702, acceleration sensor 703,angular acceleration sensor 704, fluttering control portion 705, leftand right actuators 706, center of gravity control portion 707, memoryportion 708, communication control portion 709 and antenna portion 710are driven by a current supplied from a power supply portion 711.

Though electric power is used as driving energy, a internal combustionengine may be used. An actuator utilizing physiologicaloxidation-reduction reaction as can be seen in the muscle of insects maybe used. Further, a method of obtaining energy for driving the actuatorfrom the outside may be possible. For example, a therminoic element, anelectromagnetic wave or the like may be used for the electric power.

(Method of Flight)

For simplicity of description, it is assumed that external force actingon the present fluttering sensing robot is only the fluid force receivedby the wing from the fluid and the gravity acting on the flutteringsensing robot (a product of the mass of the fluttering apparatus andgravitational acceleration). For the fluttering sensing robot to flyconstantly, it is necessary that the following relation is satisfied intime average of one fluttering operation:

(vertically upward fluid force acting on the wing)>(gravity acting onthe fluttering apparatus).

One fluttering operation means a down stroke of the wing followed by anup stroke of the wing.

For the robot to rise with the vertically upward fluid force beingdominant, the following relation must be satisfied:

(vertically upward fluid force acting on the wing in a downstroke)>(vertically downward fluid force acting on the wing in an upstroke).

Here, a method by which the vertically upward fluid force acting on thewing in a down stroke (hereinafter referred to as “fluid force for downstroke”) is made larger than the vertically downward fluid force actingon the wing in an up stroke (hereinafter referred to as “fluid force foran up stroke”) will be described, which is a method of flutteringcorresponding to but simplified from the manner of fluttering of aninsect.

For simplicity of description, the behavior of the fluid or the force ofthe fluid on the wing will be described with reference to maincomponents thereof. The magnitude of the buoyancy force obtained by thefluttering method and the gravity acting on the fluttering sensing robot(hereinafter referred to as “weight”) will be described later.

In order to make the fluid force for a down stroke larger than the fluidforce for an up stroke, the down stroke should be such that the volumeof a space in which the wing film 106 moves in the down stroke ismaximized. For this purpose, the wing film 106 should be moved downwardapproximately parallel to the horizontal plane, whereby almost maximumfluid force can be obtained.

By contrast, for the up stroke, the wing should be moved upward suchthat the volume of the space in which wing film 106 moves is minimized.For this purpose, the wing film 106 should be moved upward approximatelyat a right angle with respect to the horizontal plane, and the fluidforce exerted on the wing is approximately minimized.

Thus, assume that wing shafts 103 and 104 are reciprocated by an angle γupward and downward with the position where the shafts are alignedapproximately with the horizontal plane being the center, when the wingshafts 103 and 104 are reciprocated about the rotation axis 800 byrotary actuators 101 and 102. Further, the reciprocating motion of rearwing shaft 104 is adapted to be delayed by an appropriate phase φ fromthe reciprocating motion of the front wing shaft 103.

Accordingly, in the series of reciprocating motions of the wing shown inFIGS. 45 to 52 (representing an example where φ=20°), front wing shaft303 of rotary actuator 301 which is at a higher position is moveddownward earlier in the down stroke shown in FIGS. 45 to 48, andtherefore tip ends of front and rear wing shafts 303 and 304 and thewing film 306 come closer to horizontal.

In the up stroke shown in FIGS. 49 to 52, difference in height of thetip ends of wing shafts 303 and 304 increases and wing film 306 comescloser to vertical. As a result, the amount of fluid moved downward orupward by the wing film 306 spread across front and rear wing shafts 303and 304 becomes different. In this fluttering sensing robot, the fluidforce for the down stroke becomes larger than the fluid force for the upstroke, and hence buoyancy force is generated.

The vector of the buoyancy force inclines forward or backward bychanging the phase difference φ. When it is inclined forward, theapparatus moves forward, when it is inclined backward, the apparatusmoves backward and when it is directed directly upward, the apparatushovers. In the actual flight, it is possible to control flutteringfrequency f or fluttering angle γ, in addition to phase difference φ.Though fluttering elevation θ is fixed in the present flutteringapparatus, a function of changing this angle may be added to increasethe degree of freedom.

(Fluttering Control)

The actual fluttering control will be described in greater detail. Inthe above described fluttering apparatus, the torsion angle α providedby the tip end of the wing in the down stroke or up stroke can beapproximately represented by the following equation, where 1 representswing length (length of the wing film along the front and rear wingshafts), w represents wing width (distance between front and rear wingshafts), γ represents fluttering angle, τ represents phase of thefluttering motion (the instant of highest up stroke being 0° and thelowest down stroke being 180°), and φ represents phase differencebetween the front and rear wing shafts (see FIGS. 45 to 47):tan α=(w/1)·[ sin(γ·cos τ)−sin {γ*cos(τ+φ)}]

Actually, the front and rear wing shafts are elastic and deformable, andtherefore, the torsion angle α may vary to some extent. Further, theangle is smaller closer to the root of the wing shaft. For simplicity ofdescription, the angle α in accordance with the above equation will beused for the following discussion.

Vertical component F of the fluid force acting on the wing free oftorsion is approximately given by the following equation, where ρrepresents density of the fluid, γ represents fluttering angle and frepresents fluttering frequency.F=(4/3)·π² ρwγ ² f ² l ³·sin² τ·cos(γ·cos τ)Horizontal component of the fluid force acting on the wing is canceled,when motions of the left and right wings are the same.

When the wing has a torsion angle of α, components L and D which arevertical and horizontal to the plane of fluttering motion, respectively,of the component f can be given by:L=F·cos α·sin αD=F·cos² α

Considering elevation θ of fluttering, vertical component A that must bebalanced with gravity and horizontal component J that will be the thrustof forward/backward motion are as follows:

For the down strokeA↓=−L·cos θ+D·sin θJ↓=−L·sin θ−D·cos θ

For the up strokeA↑=L·cos θ−D·sin θL↑=L·sin θ+D·cos θActual buoyancy or thrust is given as an integration of one period ofthe fluttering motion.

Based on the foregoing, time change of the vertical component A and thehorizontal component J together with the time change of angles areplotted in FIG. 57 as an example of flight control, where the length ofthe wing of the fluttering sensing robot l=4 cm, wing width w=1 cm,fluttering elevation θ=30°, fluttering angle γ=60°, fluttering frequencyf=50 Hz, phase difference for the down stroke θ↓=4° and phase differencefor the up stroke θ↑=16°.

The abscissa represents the time corresponding to one period, as phaseτ. The former half represents a down stroke and the latter halfrepresents an up stroke. Curves of the graphs represent changes withtime of fluttering angle γf of the front wing shaft, fluttering angle γbof the rear wing shaft, torsion angle of the wing from a horizontalplane (α+θ), and vertical and horizontal components A and J of the fluidforce.

In this example, vertical component A of the fluid force per unit timeis larger in the down stroke than in the up stroke, and therefore, onewing provides vertically upward fluid force of about 500 dyn as anaverage for one period. Namely, if the weight of the fluttering sensingrobot is about 1 g or smaller, it can be lifted by two wings. Thehorizontal component J of the fluid force per unit time is almostcancelled in one period, and hence, a fluttering sensing robot havingthe weight of about 1 g can hover.

Here, when the phase difference for the down stroke φ↓ is made larger orwhen the phase difference for the up stroke θ↑ is made smaller, theapparatus can move forward. At this time, for horizontal forwardmovement, it is desired that the frequency f be reduced slightly. On thecontrary, when the phase difference for the down stroke φ↓ is madesmaller or the phase difference for the up stroke φ↑ is made larger, theapparatus can move backward. For horizontal backward movement, it isdesired that the frequency f be increased slightly.

When the phase difference for the up stroke φ↑ is kept at 16° while thephase difference for the down stroke φ↓ is enlarged to 7°, or when thephase difference for the down stroke φ↓ is kept at 4° while the phasedifference for the up stroke φ↑ is made smaller to 11° with thefluttering frequency f decreased to f=48 Hz, the fluttering sensingrobot can move horizontally forward at the speed of 1 m in the initial 1second.

When the phase difference for the up stroke φ↑ is kept at 16° and thephase difference for the down stroke φ↓ is made smaller to 1°, or whenthe phase difference for the down stroke φ↓ is kept at 4° while thephase difference for the up stroke φ↑ is enlarged to 24° with thefluttering frequency f increased to f=54 Hz, the robot can movehorizontally backward at the speed of about 1 m for the initial 1second.

In order to raise or lower the fluttering apparatus in the hoveringstate, the frequency f may be increased or decreased. During horizontalflight, upward movement and downward movement can be controlled mainlyby the frequency f. By increasing the frequency f, the flutteringsensing robot moves upward, and by lowering frequency f, the flutteringsensing robot moves downward.

In the present example, the torsion angle α of the wing is slowlychanged during an up stroke or a down stroke, in order to reduce load onthe actuator. As the fluttering motion to obtain buoyancy, the torsionangle α may be set at a predetermined value during an up stroke or downstroke and the torsion angle α may be abruptly changed at the transitionpoint from a down stroke to an up stroke or from an up stroke to thedown stroke.

FIG. 58 shows change with time of the vertical component A andhorizontal component J together with the change with time of the angles,where fluttering elevation θ=0°. This example shows a fluttering motionconceived from the hovering of a humming bird. Steering to the left orto the right may be realized by generating a difference in thrust ofleft and right wings, if it is possible to separately control flutteringmotions of the left and right wings.

For example, when the apparatus is flying forward and is to be turned tothe right, the fluttering angle γ of the right wing should be madesmaller than that of the left wing, or phase difference between thefront wing shaft and the rear wing shaft of the right wing is madelarger than that of the left wing, or alternatively, the flutteringelevation θ of the right wing should be made smaller than the left wing,if the fluttering elevation θ is controllable. Thus, the thrust of theright wing becomes lower relative to the thrust of the left wing, andhence the robot can turn to the right. When the fluttering sensing robotis to be turned to the left, the control is opposite.

When separate control of the left and right wings is not possible as inthe fluttering sensing robot shown in FIG. 55, a center of gravitycontrol portion 707 that is mounted in the fluttering apparatus shown inFIG. 56 may be mounted in the present fluttering sensing robot so as toshift the center of gravity of the fluttering sensing robot to the leftor to the right, to enable turning to the left or to the right.

For example, by shifting the center of gravity to the right, incliningthe right wing downward and the left wing upward, and by increasing thefrequency f, the fluttering sensing robot can turn to the right. Byshifting the center of gravity to the left and by increasing thefrequency f in the similar manner, the fluttering sensing robot can turnto the left. This method is also applicable when separate control of thetwo wings is possible. In any type of the fluttering sensing robot, itis desired that fluttering frequency f for the left be set to the samevalue as the fluttering frequency f for the right, so as to keep stablethe attitude of the robot.

Though a group robot system having a fluttering sensing robot used asthe sensing robot has been described in the two embodiments above, therobot is not limited thereto. Any robot may be used, including a remotecontrollable helicopter, a humanoid robot that works with two legs, or agroup robot in the shape of fish may be used, provided that the basestation can control operation, detection of an object, communication andthe like of the robot as a group robot system.

Finally, the structure and effects obtained thereby of the flutteringsensing robot (or fluttering pheromone robot) used in the group robotsystem of the present embodiments will be summarized.

The fluttering sensing robot in accordance with the present embodimentsincludes a flying body including a wing portion for flying in a spacewhere a fluid exists, a driving portion and a main body. The drivingportion causes a down stroke by which the wing portion is moved downwardfrom above, and an up stroke by which the wing portion moves upward frombelow. The wing portion is attached to the main body, and the drivingportion is mounted on the main body. As a time average of the series ofdown stroke and up stroke operations, vertically upward force among theforces exerted by the fluid to the wing portion becomes larger than thegravity acting on the flying body.

By this structure, as a time average from the down stroke to the upstroke of fluttering operation of the wing portion, vertically upwardforce among the forces exerted by the fluid on the wing portion becomeslarger than the gravity acting on the flying body, and hence buoyancyacts on the flying body. As a result, the flying body can move withouttouching the ground.

For buoyancy to act on the flying body, it is desirable that the volumeof a space in which the wing portion moves in the down stroke is largerthan the volume of the space in which the wing moves in the up stroke.When the buoyancy is balanced with the gravity acting on the flyingbody, hovering becomes possible, that is, the device can stay in the airapart from the ground.

It is desirable that the flying body is used as moving means forperforming a prescribed work indoors, or moving means for performingprescribed work outdoors.

As the flying body obtains buoyancy and can move apart from the ground,it can move in a house where there are various and many objects such aspieces of furniture of which positions are changed with time, whileavoiding such obstacles. Thus it can easily perform prescribed work suchas monitoring the condition of each room. When used outdoors, the flyingbody can move freely without any influence of obstacles at a disastersite or geography of general field, for example, and it can easilyperform a prescribed work such as information collection.

Specifically, the wing portion has a wing body and a wing shaftsupporting the wing body. Desirably, the driving portion changes atorsion angle formed by a tip end portion of the wing body and a phantomprescribed reference plane, by driving the wing shaft.

Thus, magnitude or direction of the fluid force exerted by the fluid onthe wing portion changes, so that the flying body can move upward,downward, forward or backward.

In order to make the volume of the space in which the wing portion movesin a down stroke larger than the volume of the space in which the wingportion moves in an up stroke, it is necessary for the driving portionto make different the torsion angle for the down stroke and the torsionangle for the up stroke.

Further, it is desirable that the driving portion changes with time thetorsion angle.

This enables smooth change of the attitude of the wing portion, avoidingabrupt action of the fluid force on the wing portion.

The wing shaft includes one wing shaft and the other wing shaft, thewing body includes a film formed bridging between the one wing shaft andthe other wing shaft, and it is desirable for the driving portion todrive one wing shaft and the other wing shaft separately.

Here, by driving the one wing shaft and the other wing shaft separately,the torsion angle can easily be changed.

Desirably, the wing shaft performs a reciprocating operation on aphantom plane with the driving portion being a fulcrum, the main bodyextends in one direction, and an elevation formed by the direction ofextension of the main body and the phantom plane is variable.

Here, the degree of freedom of fluttering motion becomes higher,realizing more complicated fluttering motion. By increasing theelevation and controlling torsion angle, flight at higher speed becomespossible. By making the elevation substantially 0°, hovering with highmaneuverability like a humming bird becomes possible.

Specifically, it is desired that the wing portion has a main shaft and awing body formed from the main shaft in a direction approximatelyorthogonal to the direction of extension of the main shaft, and that thedriving portion changes torsion angle formed by a phantom plane incontact with the wing body and a prescribed phantom reference planeincluding the main shaft, by driving the main shaft.

Thus, magnitude or direction of the fluid force exerted by the fluid onthe wing portion is changed, so that the flying body can move upward,downward, forward or backward.

In order to change the attitude of the wing portion by such a mainshaft, it is desirable that the driving portion includes an actuatorhaving at least three degrees of freedom.

Desirably, the wing portion is formed on one side and the other side ofapproximately the center of the main body, and that the driving portiondrives the wing portion formed on one side and the wing portion formedon the other side separately.

Here, the attitude of the wing portion formed one side and the wingportion formed on the other side can be changed separately, and hencethe direction of the flying body can be changed easily.

Further, it is desirable that the apparatus further includes a sensorportion for grasping environmental conditions, a memory portion forstoring information, or a communication portion fortransmitting/receiving information.

When a sensor portion is provided, it becomes possible to obtaininformation of position, attitude or velocity of the flying body,position or moving velocity of obstacles around the flying body, orenvironmental information such as temperature or brightness, enablingmore appropriate fluttering control. When a memory portion is provided,it becomes possible to store the obtained environmental information, andtherefore, the flying body comes to have learning function. When acommunication portion is provided, information can be exchanged betweena plurality of flying bodies and a base station, and by exchanging theobtained information, coordinated activity between each of the pluralityof flying bodies can readily be realized.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A group robot system, comprising: a plurality of sensing robots usedfor searching for an object; and a base station controlling theplurality of sensing robots; wherein wherein said plurality of sensingrobots are controlled to have different manner related to searching ofsaid object, in accordance with distance from said base station; whereinsaid sensing robot is a fluttering sensing robot capable of flyingthrough fluttering motion; and the manner related to searching of saidobject is frequency of the fluttering motion of said plurality offluttering sensing robots.
 2. The group robot system according to claim1, wherein said manner related to searching of said object also issensing resolution of each of said plurality of fluttering sensingrobots, where the sending sensing resolution is controlled in accordancewith the distance from said station.
 3. The group robot system accordingto claim 2, wherein said plurality of fluttering sensing robots includesa plurality of groups in accordance with distance from said basestation; and said plurality of fluttering sensing robots are controlledsuch that a group of fluttering sensing robots closer to said basestation has higher resolution than a group of fluttering sensing robotsfar from said base station.
 4. The group robot system according to claim2, wherein said plurality of fluttering sensing robots are controlledsuch that said fluttering sensing robot closer to said base station hashigher resolution than said fluttering sensing robot far from said basestation.
 5. The group robot system according to claim 1, wherein saidplurality of fluttering sensing robots include a plurality of groups inaccordance with distance from said base station; and said plurality offluttering sensing robots are controlled such that a group of saidfluttering sensing robots closer to said base station has lowerfrequency of fluttering motion than a group of said fluttering sensingrobots far from said base station.
 6. The group robot system accordingto claim 1, wherein said plurality of fluttering sensing robots arecontrolled such that said fluttering sensing robot closer to said basestation has lower frequency of fluttering motion than said flutteringsensing robot far from said base station.
 7. The group robot systemaccording to claim 1, wherein the manner related to searching of saidobject also is type of a detection sensor of said fluttering sensingrobot or method of processing sensor information.
 8. The group robotsystem according to claim 1, wherein: the manner related to searching ofsaid object is changed for of the one of said plurality of flutteringsensing robots which has detected said object.
 9. The group robot systemaccording to claim 8, wherein: the manner related to searching of saidobject is changed for of said sensing fluttering robots positioned in anarea around the one of said plurality of fluttering sensing robots whichhas detected said object.
 10. The group robot system according to claim8, wherein: the manner of searching of said object is changed for theone of said plurality of fluttering sensing robots which ceases todetect said object.
 11. The group robot system according to claim 10,wherein: the manner of searching of said object is changed forfluttering sensing robots positioned in an area around the one of saidplurality of fluttering sensing robots which ceases to detect saidobject.
 12. A group robot system according to claim 1, wherein: the basestation for controlling said plurality of fluttering sensing robots ismoveable; and said plurality of fluttering sensing robots search forsaid object while moving along with movement of said base station,keeping a tolerable range of positional relation with said base station.13. The group robot system according to claim 12, wherein said pluralityof fluttering sensing robots move while maintaining tolerable range ofpositional relation with each other.
 14. The group robot systemaccording to claim 12, set to move in such a state in that saidplurality of fluttering sensing robots are arranged concentrically withsaid base station positioned at the center of concentric circles. 15.The group robot system according to claim 12, wherein said base stationis set to move toward the object, when said object is detected by saidfluttering sensing robot.
 16. The group robot system according to claim12, wherein said base station moves such that there is no gap oroverlapping between search areas by said plurality of fluttering sensingrobots.
 17. The group robot system according to claim 12, wherein: saidplurality of fluttering sensing robots are configured and arranged forindependent movement; said base station is configured and arranged tocontrol said plurality of fluttering sensing robots and also to moveindependently; said plurality of fluttering sensing robots and said basestation are configured and arranged so as to be capable of search forsaid object while said base station and said plurality of flutteringsensing robots are moving, and said base station is configured andarranged to control movement of the plurality of fluttering sensingrobots with respect to the base station so that said plurality offluttering sensing robots keep a tolerable range of positional relationwith respect to said base station.
 18. A group robot system according toclaim 1, wherein: said plurality of fluttering sensing robots arecontrolled such that the manner related to searching of said object ofeach of said plurality of fluttering sensing robots is independent fromeach other.
 19. The group robot system according to claim 18, whereinindependent control of the manner related to searching of said object ofeach of said plurality of fluttering sensing robots includes control inwhich the manner related to searching of said object by each of saidplurality of fluttering sensing robots is differently fixed, inaccordance with environment.
 20. The group robot system according toclaim 1, wherein: each of said plurality of sensing fluttering sensingrobots includes a sensing device that is configured and arranged so asto be capable of sensing an object, the base station includes acontrolling device, the controlling device being configured and arrangedso to provide outputs to each of the plurality of fluttering sensingrobots so as to thereby as control the manner of searching beingimplemented by the plurality of fluttering sensing robots, where themanner of searching is controlled by the controlling device so that themanner of searching for the object is set so as to be different inaccordance with the distance between the base station and each of theplurality of fluttering sensing robots.
 21. The group robot system ofclaim 20, wherein the sensing device is operable in different operatingmodes and wherein the base station controlling device is configured andarranged to provide an output setting an operating mode from thedifferent operating modes, where the setting of the operating mode iscontrolled by the controlling device so that the set operating mode isset so as to be different in accordance with the distance between thebase station and each of the plurality of fluttering sensing robots. 22.The group robot system of claim 20, wherein: the sensing device includesa plurality of sensing devices, each sensing device being configured soas to be capable of one of being operated in a different operating modesor being capable of performing different sensing techniques; when theplurality of sensing devices are operable in different operating modes,the base station controlling device is configured and arranged toprovide an output setting an operating mode from the different operatingmodes, where operating mode is set so as to be different in accordancewith the distance between the base station and each of the pluralityfluttering sensing robots, and when the plurality of sensing devicesembody different sensing techniques, the base station controlling deviceis configured and arranged to provide an output that selects one of theplurality of sensing devices for detection of the object.
 23. A grouprobot system, comprising a plurality of sensing robots used forsearching for an object; a base station controlling said plurality ofsensing robots; and a communication system wherein said communicationsystem of said group robot system has a hierarchical structure includingsaid base station as an uppermost layer and a plurality of layers formedby said plurality of sensing robots; wherein, in said hierarchicalstructure, information related to control of each of said plurality ofsensing robots is transmitted from said base station downward throughsaid hierarchical structure to each of said plurality of sensing robots,wherein, in said hierarchical structure, information related tosearching of said object of each of said plurality of sensing robots istransmitted from each of said plurality of sensing robots upward throughsaid hierarchical structure to said base station, and wherein saidsensing robots are controlled such that manner related to searching ofsaid object differ layer by layer of said hierarchical structure. 24.The group robot system according to claim 23, wherein the manner relatedto searching of said object is sensing resolution of said sensingrobots.
 25. The group robot system according to claim 24, wherein saidplurality of sensing robots include a plurality of groups in accordancewith layers of said hierarchical structure; and said plurality ofsensing robots are controlled such that said sensing robots of saidgroup belonging to an upper layer of said hierarchical structure hashigher resolution than said sensing robots of a group belonging to alower layer of said hierarchical structure.
 26. The group robot systemaccording to claim 24, wherein said plurality of sensing robots arecontrolled such that said sensing robot belonging to an upper layer ofsaid hierarchical structure has higher resolution than said sensingrobot belonging to a lower layer of said hierarchical structure.
 27. Thegroup robot system according to claim 23, wherein the manner related tosearching of said object is speed of movement of said sensing robots.28. The group robot system according to claim 27, wherein said pluralityof sensing robots includes a plurality of groups in accordance withlayers of said hierarchical structure; and said plurality of sensingrobots are controlled such that said sensing robots of a group belongingto an upper layer of said hierarchical structure moves slower than saidsensing robots of a group belonging to a lower layer of saidhierarchical structure.
 29. The group robot system according to claim27, wherein said plurality of sensing robots are controlled such thatsaid sensing robot belonging to an upper layer of said hierarchicalstructure moves slower than said sensing robot belonging to a lowerlayer of said hierarchical structure.
 30. The group robot systemaccording to claim 23, wherein said sensing robot is a flutteringsensing robot capable of flying through fluttering motion; and themanner related to searching of said object is frequency of flutteringmotion of said fluttering sensing robot.
 31. The group robot systemaccording to claim 30, wherein said plurality of fluttering sensingrobots includes a plurality of groups in accordance with layers of saidhierarchical structure; and said plurality of sensing robots arecontrolled such that said fluttering sensing robots of a group belongingto an upper layer of said hierarchical structure have lower frequency offluttering motion than said fluttering sensing robots of a groupbelonging to a lower layer of said hierarchical structure.
 32. The grouprobot system according to claim 30, wherein said plurality of flutteringsensing robots are controlled such that said fluttering sensing robotbelonging to an upper layer of said hierarchical structure has lowerfrequency of fluttering motion than said fluttering sensing robotbelonging to a lower layer of said hierarchical structure.
 33. A grouprobot system, comprising: a plurality or sensing robots used forsearching for an object; a base station controlling the plurality ofsensing robots; wherein said plurality of sensing robots are controlledto have different manner related to searching of said object, inaccordance with distance from said base station; wherein said mannerrelated to searching of said object is sensing resolution of each ofsaid plurality of sensing robots, where the sensing resolution iscontrolled in accordance with the distance from said base station;wherein said plurality of sensing robots includes a plurality of groupsin accordance with distance from said base station; and wherein saidplurality of sensing robots are controlled such that a group of sensingrobots closer to said base station has higher resolution than a group ofsensing robots far from said base station.
 34. A group robot system,comprising: a plurality of sensing robots used for searching for anobject; a base station controlling the plurality of sensing robots;wherein said plurality of sensing robots are controlled to havedifferent manner related to searching of said object, in accordance withdistance from said base station; wherein said manner related tosearching of said object is sensing resolution of each of said pluralityof sensing robots, where the sensing resolution is controlled inaccordance with the distance from said base station; and wherein saidplurality of sensing robots are controlled such that said sensing robotcloser to said base station has higher resolution than said sensingrobot far from said base station.
 35. A group robot system, comprising:a plurality of sensing robots used for searching for an object; a basestation controlling the plurality of sensing robots; wherein saidplurality of sensing robots are controlled to have different mannerrelated to searching of said object, in accordance with distance fromsaid base station; wherein the manner related to searching of saidobject is speed of movement of each of said plurality of sensing robots;wherein said plurality of sensing robots includes a plurality of groupsin accordance with distance from said base station; and wherein saidplurality of sensing robots are controlled such that a group of saidsensing robots closer to said base station move slower than a group ofsaid sensing robots far from said base station.
 36. A group robotsystem, comprising: a plurality of sensing robots used for searching foran object; a base station controlling the plurality of sensing robots;wherein said plurality of sensing robots are controlled to havedifferent manner related to searching of said object, in accordance withdistance from said base station; wherein the manner related to searchingof said object is speed of movement of each of said plurality of sensingrobots; wherein said plurality of sensing robots are controlled suchthat said sensing robot closer to said base station moves slower thansaid sensing robot far from said base station.